Glossary

abaxial

the side of a lateral structure that faces away from the axis on which the structure is borne. In relation to fronds the abaxial suface is the lower suface. (ant. adaxial ; cf. ventral ).

abaxially

see abaxial.

abrupt

suddenly narrowed or cut off. (ant. decrescent ; cf. truncate ).

abscissent

having fronds or parts of fronds that dry and fall from the rhizome or axis during the seasons unfavourable for growth; applied to most temperate and cold climate ferns and to some tropical species that grow in seasonally dry regions. (syn. deciduous ).

abscission

the separation of major plant parts such as fronds from rhizomes or pinnae from rachises as a result of natural structural and chemical changes (see abscission layer). These changes can be a consequence of natural ageing (senescence ) or a response to desiccation or disease. (cf. abscissent; senescence ).

abscission layer

a thin region of thin-walled cells, the senescence and death of which cause the separation of two plant parts such as a stipe from a rhizome or phyllopodium, a pinna from a rachis or a pinnule from a costa . (cf. abscission, articulation, senescence ).

accessory

supplementary, applied especially to axes or lamina divisions that are in an atypical position, eg. the sessile branches subtending larger portions of the lamina in some Dicranopteris species and the sessile segments on the axes of some Pteridium species .

achlorophyllous

lacking chlorophyll. (cf. chlorophyllous ).

acicular

needle-shaped; short and sharp-pointed, such as the hairs found in the adaxial sulcus of many species of Thelypteridaceae.

acidophilous

growing or prospering in a low pH substrate, such as bog soils or soils derived from sandstone, quartzite, or granite. (cf. calcicolous ).

acropetal

maturing in succession from the base of a structure towards its apex . (ant. basipetal ).

acrophyll

a distal, adult frond of certain hemiepiphytic ferns with heterophyllous sterile fronds, especially Teratophyllum. (cf. bathyphyll ).

acroscopic

facing or directed toward the apex of the axis on which the structure is borne. (ant. basiscopic ; cf. distal ).

acrostichoid

producing sporangia apparently or actually scattered on the surface of the fertile lamina , usually densely so, as in Bolbitis, Elaphoglossum and Acrostichum.

aculeate

(1) having narrowly conical, sharp-pointed projections, as the stipe bases of certain Cyatheaceae. (n. aculeus ; syn. prickly ; ant. inermous ; cf. muricate, tuberculate); (2) bearing bullae that are no higher than wide, broadly attached, and with an acute apex . (cf. colliculate, gemmulate, patellate, pustulate ).

acuminate

forming an angle of less than 30° with the two sides somewhat concave . (cf. acute, attenuate, obtuse ).

acute

forming an angle of 30–90° with the two sides straight or slightly convex . (cf. acuminate, attenuate, obtuse ).

adaxial

the side of a lateral structure that faces toward the axis on which the structure is borne. In relation to fronds the adaxial suface is the top suface. (ant. abaxial; cf. dorsal ).

adjacent

next to each other, but not overlapping or touching.

adnate

broadly attached to a dissimilar structure, such as the pinnae of a pinnatisect frond to the rachis . (cf. connate, free ).

adult

having the most fully developed morphology. (ant. juvenlle).

adventive

partially naturalized from an accidental introduction. (cf. escaped, introduced, naturalized ).

aerial

above ground. (ant. subterranean ; cf. epigeous, hypogeous ).

aerophore

an often evanescent spot, swelling, or finger-like projection of thin-walled cells found along the stipe or in the pinna or pinnule axils of some ferns, especially Thelypteridaceae, that apparently aids gas exchange with the atmosphere. (cf. hydathode ).

aggregated

clustered.

ala

a wing; a usually long, narrow membrane or section of lamina laterally bordering a stipe, rachis, or costa . (pl. alae ; adj. alate ).

alae

plural of ala .

alate

bearing a wing (ala ). (n. ala ; n.pl. alae ; ant. exalate ).

allopolyploid

a polyploid whose chromosomes were contributed by two or more species . (cf. autopolyploid ).

alternate

having one structure, in ferns usually a pinna, inserted at a single point along an axis . (cf. opposite, verticillate ).

amphibious

capable of growing on dry land or in water, often applied to plants of seasonally inundated areas. (cf. aquatic, terrestrial ).

anadromous

with the basal pinnule and/or basal vein group of the pinna directed toward the frond apex . (cf. catadromous, isodromous ).

anastomosing

joining together to form a mesh or network and enclose areolae; usually applied to veins and muri . (ant. free ).

angustate

gradually narrower to the apex . (syn. gradual, tapered ; cf. decrescent ).

annular

pertaining to the annulus .

annuli

plural of annulus .

annulus

a row or patch of partially or entirely thick-walled cells of the capsule of the leptosporangium that contracts or breaks and permits the capsule to open and to discharge its spores. (pl. annuli ; adj. annular ; cf. stomium ).

antepenultimate

two before the last (i.e. the one immediately before the penultimate), in a series . (cf. penultimate ).

antheridium

the male sex organ of pteridophytes borne on the gametophyte and producing spermatozoids. (pl. antheridia ; cf. archegonium ).

antrorse

directed sharply towards the apex, commonly applied to hairs and cilia . (ant. retrorse ).

apex

the distal, terminal portion of a structure. (pl. apices ; adj. apical ; syn. tip ; ant. base ).

aphlebia

a highly divided, skeletonized, anomalous, pinna-like structure on the stipe of certain ferns, especially in Cyatheaceae. (pl. aphlebiae ).

aphlebiae

plural of aphlebia .

apical

at or pertaining to the apex or tip , especially of complex structures or organs like roots, rhizomes, or fronds. (n. apex ; n.pl. apices ; ant. basal ; cf. lateral, terminal ).

apices

plural of apex .

apiculate

abruptly terminating in a small, triangular apex . (cf. cuspidate, mucronate ).

apogamy

the formation of a sporophyte from a gametophyte by direct asexual development rather than by fertilization of gametes. (adj. apogamous ).

appendage

a subsidiary part, usually projecting or pendent .

appressed

tightly pressed against a surface. (cf. ascending, patent, reflexed ).

approximate

closely spaced, and so nearly touching. (cf. contiguous, distant, imbricate ).

aquatic

growing in water, rooted in the substrate or free -floating. (cf. amphibious, rheophytic, terrestrial ).

arborescent

having the habit of a tree, with an obvious caudex, found especially in many species of Cyatheaceae.

archegonium

the female sex organ of pteridophytes borne on the gametophyte and producing ova . (pl. archegonia ; cf. antheridium ).

areola

(1) an area enclosed by a ring of veins and with or without one or more free included veinlets; (2) also used to describe spore onamentation in which areas of the spore surface are enclosed by muri (see retate ).

areolae

plural of areola .

areolate

having areas enclosed by a mesh or network of anastomosing veins. (n. areola ; n.pl. areolae ).

areoles

an alternative spelling of areolae .

arista

a long, stiff, bristle-like apical prolongation of a midrib beyond the margin, as on the apices of segments in Arachnoides and Polystichum (adj. aristate ; pl. aristae ).

aristae

plural of arista .

aristate

bearing a long, stiff, bristle-like apical prolongation of a midrib beyond the margin, as on the apices of segments in Arachnoides and Polystichum (n. arista ; n.pl. aristae ; cf. mucronate ).

arm

a non-ultimate branch of a stellate hair . (cf. pedicel, ray ).

articulate

having an articulation . (syn. jointed ; ant. exarticulate ).

articulation

in some ferns, a swollen joint-like abscission zone (containing an abscission layer) at the junction of a stipe and rhizome, a stipe and phyllopodium or a rachis and pinna; (2) an obvious , thickened, discoloured, weakened, or constricted area at the nodes of Equisetum stems or proximal to the nodes of some Selaginella stems that may serve to fragment the plant and promote its dispersal. (adj. articulate ; syn. joint ; cf. abscission layer).

ascending

(1) at an angle from within the substrate, usually a short rhizome that bears approximate stipe bases, usually on all sides. (cf. erect, repent (creeping)); (2) obliquely directed away from a surface and towards the apex of the structure on which it is borne. (cf. appressed, patent, reflexed ).

aseptate

not divided by septa (ant. septate ).

aspidote

bearing peltate scales. (cf. furfuraceous, paleaceous , squamous).

asymmetric

having a different outline on each side of a central axis . (ant. symmetric ).

atrocastaneous

dark brown tinged with red; dark chestnut-coloured.

atropurpureous

purplish-black.

attenuate

forming an angle of less than 15°, narrowly tapering. (cf. acuminate, acute, obtuse ).

auricle

a rounded or sometimes elongate lobe or ear, usually at the base of a lamina, pinna, or pinnule or along the stipe . (adj. auriculate ).

auriculate

having one or more auricles. (n. auricle ; ant. exauriculate ).

autoallopolyploid

an allopolyploid whose chromosomes have doubled.

autopolyploid

a polyploid whose chromosomes were contributed by only one species . (cf. allopolyploid ).

awn

in ferns, a small, slightly flattened, bristle-like appendage on the adaxial side of a rachis or costa , found especially in certain Pteris species .

axes

plural of axis .

axil

the acroscopic region (angle) formed by the point of insertion of a minor axis on a major one, especially of a pinna on a rachis . (adj. axillary ).

axillary

pertaining to an axil .

axis

(1) a general term for stipe, rachis, midrib, costa, costule , etc. (pl. axes ); (2) the central line or structure along which parts or organs are arranged. (pl. axes ).

baculate

bearing stelae that are at least 1.5 x longer than wide, cylindrical, and with usually an obtuse to round apex . (cf. clavate, echinate, saccate, tuberculate, verrucate ).

basal

at the base or pertaining to the base . (n. base ; ant. apical ).

base

the proximal portion of a structure, that part nearest the point of attachment. (adj. basal ; ant. apex ).

basifixed

attached at the base ; commonly applied to scales.

basionym

a valid name whose epithet is transferred when making a new combination .

basipetal

maturing in succession from the apex of a structure towards its base . (ant. acropetal ).

basiscopic

facing or directed toward the base of the axis on which the structure is borne. (ant. acroscopic ; cf. proximal ).

bathyphyll

a proximal, juvenile frond of certain hemiepiphytic ferns with heterophyllous fronds, especially Teratophyllum. (cf. acrophyll ).

biauriculate

bearing two auricles, eg. the rhizome scales or pinnae of certain Polypodiaceae. (cf. uniauriculate ).

bicellular

formed of two cells. (cf. unicellular, paucicellular, multicellular ).

bicolorous

having two colors, usually applied to rhizome scales that have a central stripe or region that is decidedly different in color from the borders. (ant. concolorous ).

bifid

divided into two similar parts, but not nearly to the base . (cf. bipartite, quadrifid, quadripartite ).

bifurcate

divided once into two equal or subequal branches, applied especially to laminae and to simply branched hairs. (syn. forked ; cf. stellate). The term twice-bifurcate is applied to more complex hairs that branch dichotomously twice. i.e. they fork above the base (from the apex of the pedicel) into two arms, and each arm forks into two equal or subequal rays. (cf. stellate, twice-stellate ).

bilabiate

two-lipped, usually applied to the involucres of Hymenophyllum and some species of Trichomanes and to the indusia of some other genera.

bilateral

symmetrical on opposite sides of an axis . (cf. unilateral ).

bipartite

divided into two similar parts to or nearly to the base . (cf. bifid, quadrifid, quadripartite ).

bipinnate

divided into pinnae bearing pinnules that are more-or-less entire . (cf. pinnate, quadripinnate, tripinnate ).

bipinnatifid

pinnate with pinnae lobed more than half way to their costae .

bipinnatisect

divided into pinnae with the pinnae pinnatisect . (syn. pinnate-pinnatisect ).

biseriate

disposed in two rows. (cf. multiseriate, uniseriate ).

bisulcate

having two longitudinal grooves, especially on the adaxial side of the stipe, rachis, or costa . (cf. sulcate, trisulcate ).

bivalvate

having or consisting of two valves or similar parts as the involucres of many Hymenophyllaceae, the indusia of Cibotium or the sporangia of Osmundaceae.

blunt

somewhat rounded , but neither cut off sharply nor pointed.

border

the marginal and submarginal parts of a structure, especially of bicolourous scales. (cf. central band, margin ).

branch

(1) a subordinate division from a main stem; in Equisetum, one of few to many small stems forming whorls at intervals along the larger, main stem. (adj. branched ; dim. branchlet); (2) in the Gleicheniaceae, an axis subtending a bud, formed in pairs and further designated by its order (ultimate, penultimate, or antepenultimate) and whether it bears segments (pectinate, partially pectinate, or nude ).

branchlet

diminutive of branch .

bristle

a stiff, paucicellular, usually straight, terete, and dark-coloured epidermal outgrowth one cell wide distally and often a few cells wide at the base . (adj. bristly ; cf. scale, squamule ).

brittle

breaking or shattering easily when bent.

bud

in pteridophytes, a non-deciduous, unspsecialized, multicellular, often irregular mass of tissue produced by a gametophyte that grows and forms an apogamous sporophyte . (cf. bulbil, gemma ).

bulbiferous

bearing one or more bulbils. (n. bulbil ; syn. viviparous ; cf. gemmiferous ).

bulbil

a small, usually persistent, more or less globular, usually hairy or scaly, asexual propagule borne on a rachis or costa or occasionally a lamina margin that is capable of forming a plantlet before, during, or after frond senescence, or after separation from the frond , as in certain Asplenium, Bolbitis, Diplazium, Polystichum and Tectaria species . (adj. bulbiferous ; syn. bulblet ; cf. bud, gemma ).

bulbous

swollen, but without being spherical (cf. globular ).

bulla

a general term for a radially symmetrical low protuberance (no higher than wide); usually applied to spore ornamentation and the basis of many more specialized terms such as aculeate, colliculate, gemmulate and pustulate . (cf. stela, murus, cavus ).

bullae

plural of bulla .

bullate

having an expanded base swollen like a blister, typical of some laminar scales in Ctenitis and Cyathea.

bulliform

bearing bullae ; a general term encompassing many more specialized terms. (n. bulla ; n.pl. bullae ; cf. caviform, muriform, steliform ).

caducous

early deciduous , even prior to the maturation of the structure on which it is borne. (syn. fugacious ; cf. deciduous, persistent ).

caespitose

growing in tufts.

calathiform

having the aspect of a narrow-bottomed vase or shuttlecock, with a cluster of fronds arising from a short, erect rhizome, as in some species of Dryopteris. (cf. nidiform ).

calcicolous

growing or prospering in a high pH substrate, such as soils derived from limestone or dolomite. (cf. acidophilous ).

campanulate

bell-shaped; usually applied to the involucres of some Hymenophyllaceae, especially species of Trichomanes and Vandendoschia. (cf. peltate, pseudopeltate, bilabiate ).

canaliculate

channeled; having a small groove, especially on the adaxial side of a costule or costulet . (cf. sulcate ).

capitate

terminated by a bulbous to spherical swollen area (in unicellular glands) or cell (in multicellular glands).

capsule

the subspherical, ovoid, or slightly angular part of a sporangium that contains the spores. (cf. pedicel ).

carina

a sharp, longitudinal ridge, as on the abaxial side of the midrib in some species of Asplenium and Loxogramme. (adj. carinate ; syn. keel ).

carinate

having a carina (keel ). (n. carina ; syn. keeled ).

cartilaginous

thick and slightly flexible.

castaneous

medium brown tinged with red; chestnut-coloured.

catadromous

with the basal pinnule and/or basal vein group of the pinna directed toward the frond base . (cf. anadromous, isodromous ).

catenate

like a chain composed of links; in hairs, with adjacent cells collapsed at right angles to each other and often the end walls of the cells thickened or dark-coloured, as on some Ctenitis fronds. (syn. ctenitoid, jointed ).

caudate

bearing a narrow, elongate, tail-like appendage or apex .

caudex

an erect, trunk-like rhizome found in arborescent and subarborescent ferns, such as Cyathea and some species of Diplazium. (pl. caudices ).

caudices

plural of caudex .

cavi

plural of cavus .

cavifom

having cavi ; a general term encompassing several more specialized terms. (cf. bulliform, muriform, steliform )

cavus

a general term for a shallow, steep-sided, indentation (crater); usually applied to spore ornamentation and the basis of several more specialized terms such as foveate and foveolate . (pl. cavi ; cf. bulla, murus, stela ).

central band

the differently coloured and often thickened central cells of bicolorous scales (cf. border ).

character

a feature of an organism. (syn. characteristic, character state).

chartaceous

having the texture of thick and rigid writing paper. (cf. coriaceous, membranaceous, papyraceous ).

chlorophyllous

green because it contains chlorophyll.

chromosome

one of a definite number of bodies bearing hereditary information (DNA) that divide and are usually equally partitioned into daughter cells during cell division .

cilia

plural of cilium .

ciliate

bearing flexible, thin, usually straight hairs, as the microphyll margins of many Selaginella species . (n. cilium ; n.pl. cilia ; dim. ciliolate ; ant. eciliate ; cf. cincinnate, setose ).

ciliform

having the form of a cilium, a flexible, thin, often straight marginal hair (n. cilium ; n.pl. cilia ; cf. setiform ).

ciliolate

diminutive of ciliate .

cilium

a flexible, thin, often straight marginal hair . (pl. cilia ).

cincinnate

bearing soft, somewhat curly hairs, such as the rhizome scales of certain species of Sticherus and Oleandra. (cf. ciliate, setose ).

circinate

having an apical spiral in a single plane with the axis and with the developing apex at the center of the spiral, the typical vernation of ferns. (cf. convolute ).

clasping

embracing or surrounding the axis .

clathrate

lattice-like; having thick lateral (adjacent) cell walls and thin surficial walls, especially applied to rhizome scales of Asplenium, Ctenitis and some Polypodiaceae and Pteridaceae.

clavate

(1) club-shaped; round at the apex, widest just below the apex, and tapering gradually to the base; (2) bearing stelae that are narrow, higher than wide, and widest at or near their obtuse apex . (cf. baculate, echinate, saccate, tuberculate, verrucate ).

clubmoss

a common name for any species in the lycophyte family Lycopodiaceae (which in Thailand is represented by Lycopodium, Lycopodiella and Huperzia).

coalescent

fusing; marked uniting of originally separate structures during their subsequent development. (cf. confluent, connivent, discrete ).

coenosori

plural of coenosorus .

coenosorus

a compound sorus composed of several contiguous sori fused end-to-end (pl. coenosori ; cf. synangium ).

colliculate

bearing bullae that are contiguous, broadly attached, no higher than wide, and with an obtuse to round apex . (cf. aculeate, gemmulate, patellate, pustulate ).

combination

a name consisting of a generic name and one or two epithets below that level, one at the species level sometimes followed by one below the species level.

commissural

joined or seamed; in ferns, a commissural vein joins parallel, otherwise free veins along the lamina margin and often underlies a continuous, marginal coenosorus . (n. commissure ).

compital

at the intersection of several veins, applied to sori .

complanate

(1) flattened, usually in a horizontal plane, such as that of a lamina ; (2) at the same level as the surface. (syn. flush ; cf. immersed, impressed, prominulous, superficial ).

complete

fully developed over its usual length or area. (ant. incomplete ).

compound

composed of two or more similar parts; in laminae, pinnate or more divided. (cf. decompound, simple ).

concave

curved inwardly. (cf. convex ).

concolorous

being completely or nearly uniform in color. (ant. bicolorous ).

conduplicate

having approxirnately equal lateral halves folded together abaxially .

confluent

converging; growing near to and eventually touching, commonly applied to sori . (cf. coalescent, connivent, discrete ).

conform

(1) similar in shape and size to others, commonly applied to an apical pinna in comparison with the lateral pinnae . (ant. difform); (2) having all cells of the body similar in shape and orientation, as the rhizome scales of Sphaeropteris. (cf. marginate ).

congested

crowded; accumulated into a point or region.

conical

cone-shaped, with the base of the cone basal . (cf. obconical ).

connate

joined, usually laterally, to a similar structure, such as the fusion of pinnae towards the apex of a frond or the fusion of pinnules towards the apex of a pinna . (cf. adnate, free ).

connivent

coming together, but not joined, commonly applied to veins from two or more vein groups that approach one another, often at a sinus , but do not join. (cf. coalescent, confluent, discrete ).

contiguous

having the parts touching. (cf. approximate, distant, imbricate ).

continuous

not interrupted or broken. (ant. interrupted ).

contorted

irregularly twisted; distorted.

contracted

narrowed or shortened, often applied to subdimorphic fertile laminae or pinnae . (ant. expanded ).

convex

curved outwardly. (cf. concave ).

convolute

having two lateral spirals opposite each other, one from each edge of an axis (as seen in transverse section), without apices developing at their center, the typical vernation of Ophioglossum. (cf. circinate ).

cordate

heart-shaped; or bearing a pair of broadly rounded , sometimes overlapping lobes. (cf. hastate, sagittate ).

cordiform

heart-shaped.

coriaceous

leathery in texture and thick. (cf. chartaceous, membranaceous, papyraceous ).

correct

the legitimate name that must, under the Code (ICBN), be adopted for a taxon with a particular rank, position, and circumscription. (ant. incorrect ; cf. legitimate, valid ).

costa

the major axis of a pinna. Some authors prefer to use the term pinna-rachis instead of costa when the pinna is pinnate or more divided. (syn. pinna-rachis ; pl. costae ; adj. costal ; cf. costule, costulet ).

costae

plural of costa .

costate

having a costa or midrib . (ant. ecostate ).

costulate

having a costule . (ant. ecostulate ).

costule

the major axis of a pinnule . (adj. costular ; cf. costa, costulet ).

costulet

the major axis of a pinnulet . (cf. costa, costule ).

crenate

having rounded teeth; shallowly scalloped in a single plane . (dim. crenulate ; cf. dentate, serrate ).

crenulate

diminutive of crenate.

crispate

irregularly curled. (cf. entire, repand, sinuate, undulate ).

crista

see cristate (pl. cristae ).

cristae

plural of crista .

cristate

bearing muri that are narrow, sharp-edged, non-anastomosing, and do not form areolae . (n. crista ; n.pl. cristae ; cf. retate, reticulate, rugate ).

crozier

the young, unexpanded, circinate apex of a fern frond .

cuneate

wedge-shaped; forming an angle of 30—45° with the two sides straight.

cuspidate

bearing a short, sharp, narrowly triangular point terminating an obtuse to truncate apex . (n. cusp ; cf. apiculate, mucronate ).

decaploid

a plant that has ten sets of chromosomes.

deciduous

detaching, usually between maturity and senescence . (cf. caducous, abscissent, persistent ).

decompound

several times divided; in laminae, those that are tripinnate or more divided. (cf. compound, simple ).

decrescent

gradually narrower to the base . (syn. gradual, tapered ; ant. abrupt ; cf. angustate ).

decumbent

lying on the substrate and mostly rooted, except with the apex erect or ascending . (cf. procumbent, prostrate, sarmentose ).

decurrent

extending basiscopically on and adnate to an axis . (cf. surcurrent, sursumcurrent ).

dehiscent

splitting open or capable of doing so. (ant. indehiscent ).

delicate

fragile; easily broken. (ant. robust ).

deltate

broadly triangular with an obtuse apex .

dentate

having usually broad teeth that are directed outward from the margin, not acroscopically . (dim. denticulate ; cf. crenate, entire, serrate, toothed ).

denticulate

bearing small teeth formed by prolongations of one or two cells of the scale margin as in some Diplazium; also said of clathrate scales in which the end walls of the marginal cells are thickened and so appear to be teeth, as in Aspleniaceae.

depauperate

dwarfed in development due to poor growing conditions.

description

a lengthy statement (in Latin for new taxa) of the characters of a taxon that permit a reader to develop a mental image of the taxon . (cf. diagnosis ).

determinate

genetically limited in growth, and so usually regular in size or shape. (ant. indeterminate ).

diagnosis

a brief statement (in Latin for new taxa) emphasizing the distinctive characters of a taxon that distinguish it from related taxa . (cf. description ).

dichotomous

(1) in relation to frond complexity: a pattern of branching in which there are only two branches at each fork and the two branches are equal (more-or-less) in size, shape, and position, such as in Psilotum (n. dichotomy ; cf. pseudodichotomous); (2) in relation to venation: a branching pattern in which the two veins resulting from each fork are free and more-or-less equal. (n. dichotomy ; cf. pinnate )

difform

different in shape and/or size from others, commonly applied to an apical pinna in comparison with the lateral pinnae . (ant. conform ).

diffuse

distributed rather evenly and distantly. (syn. scattered ).

digitate

having four or more divisions all radiating narrowly from a single point, somewhat like the fingers of a hand. (cf. palmate, ternate ).

dimidiate

halved diagonally, with usually one half rudimentary or partially absent, as the pinnae or pinnules of certain Adiantum and Lindsaea species .

dimorphic

having two shapes or sizes, commonly applied to fertile versus sterile laminae or portions of laminae. (cf. hemidimorphic, monomorphic, polymorphic, heterophyllous).

diploid

a plant that has two sets of chomosomes.

dissected

deeply divided into many parts.

distal

toward or near the apex. (cf. acroscopic, medial, proximal).

distant

having similar parts that are well separated and not overlapping or touching, usually applied to stipes, pinnae, pinnules, or segments. (syn. remote; cf. approximate, contiguous, imbricate).

divaricate

widely divergent; inclined markedly away from each other. (cf. divergent, spreading).

divergent

inclined somewhat away from each other. (cf. divaricate, spreading).

division

a major category of plants, such as Tracheophyta (all vascular plants) or Pteridophyta (all spore-bearing vascular plants).

dodecaploid

a plant that has twelve sets of chromosomes.

dormant bud

in the Gleicheniaceae, a bud borne at the apex of an axis that is flanked by two branches; it does not break dormancy and so terminates its axis. (cf. latent bud).

dorsal

the upper side of a horizontal axis, such as a creeping rhizome, or of a plane non-vascular structure, such as a gametophyte. (ant. ventral; cf. abaxial, adaxial).

dorsifixed

attached by the back (not by the base), such as the elongate rhizome scales of some species of Campyloneurum. (cf. basifixed, peltate).

dromy

in pinnate or more dissected laminae, the direction of basal axes or veins with respect to the second larger order of axes, such as the direction (acroscopic or basiscopic) of a basal pinnule with respect to a rachis.

dull

see matte.

echinate

bearing stelae that are higher than wide, narrowly conical, widest near the base, and with an acute to attenuate apex. (dim. echinulate; cf. baculate, clavate, saccate, tuberculate, verrucate).

echinulate

diminutive of echinate.

eciliate

lacking cilia. (ant. ciliate).

ecostate

lacking a costa or midrib. (ant. costate).

ecostulate

lacking a costule. (ant. costulate).

egg

see ovum.

elaminate

lacking expanded lamina tissue, sometimes by reduction entirely to axes, as in the fertile portions of Osmunda fronds. (ant. laminate).

elater

each one of four strap-shaped appendages found on Equisetum spores.

eligulate

lacking a ligule. (cf. ligule, ligulate).

ellipsoid

a solid structure that is elliptical in longitudinal section.

elliptic

having the outline of an elongate circle.

elongate

longer than wide, from slightly to greatly so. (cf. isodiametric).

elongate-reniform

see hippocrepiform; a reniform indusium that is elongate (or horse-shoe shaped), compared to a reniform indusium that is more circular. (syn. hippocrepiform; cf. round-reniform).

emarginate

having a broad and shallow sinus at the nearly truncate apex of a segment, lobe, or tooth. (cf. retuse).

emersed

growing partly out of the water. (cf. submersed).

endemic

having a restricted distribution compared with a larger area, such as being confined to a single locality, country, or region.

endospore

the inner, pectocellulose layer of the spore wall that lies between the cytoplasmic membrane that surrounds the contents of the spore and the exospore. (syn. intine; cf. epispore, exospore, perispore).

entire

having an even or smooth margin (not toothed or lobed) and with or without marginal hairs or cilia. (cf. crispate, repand, sinuate, undulate).

epidermis

the outermost layer of cells of the plant that lacks intercellular spaces, contains stomates, and serves to protect the plant, to selectively exchange gases, and to retard water loss by producing a wax-like cuticular layer or by being impregnated with a wax-like substance. (adj. epidermal).

epigeous

growing above or on the surface of the ground, commonly applied to horizontal rhizomes. (ant. hypogeous; cf. subterranean, aerial).

epiphytic

growing on another plant, usually the trunk or branches of a shrub or tree. (n. epiphyte; cf. hemiepiphytic).

epispore

an outer, sporopollenin layer of the spore wall that is external to the exospore in some heterosporous ferns and Equisetum. (cf. endospore, exospore, perispore).

epithet

a typically descriptive or commemorative word, usually an adjective but sometimes a noun in apposition, that is combined with the name of a genus to form the name of a taxon, or with the name of a species to form the name of an infraspecific taxon.

equilateral

equal on both sides of an axis. (ant. inequilateral).

erect

vertical or upright from within the substrate, often producing a cluster of fronds in a basket or shuttlecock-like arrangement, with approximate stipe bases on all sides. (cf. ascending, repent (creeping)).

erose

irregularly cut away and appearing eroded, applied to the margins of scales and indusia.

escaped

partially naturalized after a deliberate introduction. (cf. adventive, introduced, naturalized).

eusporangiate

having eusporangia, not leptosporangia. (ant. leptosporangiate).

eusporangium

found in all vascular plants including lycophytes but excluding most ferns, a thick-walled, thick-pedicelled sporangium bearing thousands of spores, and lacking an annulus. (pl. eusporangia, adj. eusporangiate. cf. leptosporangium). Eusporangia are found only in 4 fern families: Equisetaceae, Marattiaceaee, Ophioglossaceae and Psilotaceae.

evanescent

(1) completing its growth cycle in a short period of time, such as species adapted to seasonally wet habitats. (2) said of structures that are conspicuous for a short period and then disappear, such as the aerophores of some species.

exalate

lacking an ala. (ant. alate).

exauriculate

lacking an auricle or auricles. (ant. auriculate).

excurrent

running or pointing towards the margin, or outwards or away from the point of origin, usually applied to veinlets. (cf. recurrent).

exhydathodous

lacking hydathodes. (ant. hydathodous).

exindusiate

lacking an indusium. (ant. indusiate).

exospore

the middle, principal sporopollenin layer of the spore wall, external to the endospore and internal to the perispore. (syn. exine; cf. endospore, epispore, perispore).

expanded

increased in area or size. (ant. contracted).

exserted

projecting beyond another structure, applied especially to the filiform receptacle of many Trichomanes species.

exstipitate

lacking a stipe, and so having the rachis joined directly to the rhizome. (syn. sessile; ant. stipitate).

extrorse

facing or opening towards the margin (away from a central axis) or apex (acroscopically), usually applied to indusia. (ant. introrse).

fabaeform

bean-shaped, said of spores. (cf. reniform).

falcate

sickle- or scythe-shaped; asymmetrically curved and tapered.

family

the principal rank of taxa between order and genus; the totality of genera that are more closely related to one another than they are to any other genera of other families.

farina

a white, yellow, or other coloured, usually thick, powdery-appearing exudate of glands, especially on the underside of the lamina in Pteridaceae. (adj. farinose).

farinose

having a white, yellow, or other coloured, usually thick, powdery-appearing exudate of glands, especially on the underside of the lamina in Pteridaceae. (n. farina; syn. ceraceous; cf. glaucous, pruinose).

fasciculate

in a closely set cluster, as if from a single point, commonly applied to hairs or stipes.

fern-allies

a popular but outdated term used for a paraphyletic assemblage of spore-bearing (seedless) vascular plants that were all believed to be closely related to true ferns. The term referred to horsetails, whisk ferns, quillworts, clubmosses and spikemosses. Nowadays, horsetails and whisk ferns are regarded as true-ferns (monilophytes) and the quillworts, clubmosses and spikeworts (now collectively called lycophytes) are believed to be very distantly related to these. (cf. lycophytes, monilophytes, pteridophytes).

fern-ally

see fern-allies.

ferrugineous

rust-coloured.

fertile

(1) in relation to sporophytes: producing sporangia and presumably viable spores. (ant. sterile); (2) in relation to gametophytes: producing gametes and/or gametangia. (ant. sterile).

fibrillose

appearing to be composed of fibers, as the rhizome scales of many Dryopteridaceae.

filamentose

a modifying term indicating the presence of long filaments borne on the principal surface ornamentation, as in Lecanopteris.

filamentous

composed of or resembling thread-like structures, such as the gametophytes of Trichomanes. (ant. thalloid).

filiform

thread-like. (cf. funiform, restiform).

fimbriate

a modifying term indicating the presence of elaborated processes at the apex of projecting ornamentation, as the cristate-fimbriate spores of certain Elaphoglossum and Oleandra species.

firm

resistant to bending or breaking; between stiff and flexible in elasticity.

flabellate

fan-shaped or fan-like; used to describe frond shape or venation (i.e. veins of equal size radiating from a single point without a prominent central axis).

flaccid

limp or flabby.

flagelliform

whip-shaped, and so tapered to the apex.

flexuous

curved or bent slightly in alternate directions; gently zig-zag. (cf. fractiflex).

form

a rank of taxa subordinate to the species and used for minor variants, such as different colour forms, that are scattered throughout the geographic range of the species; commonly the lowest category in the hierarchy of infraspecific taxa.

fossulate

bearing muri that are long, low, and parallel, with sulci between them that are narrower than the muri, as in the spores of Anemia. (cf. pleurate, rivulate).

foveate

bearing cavi that are round or nearly so and separated by distances approximating their diameter. (cf. foveolate).

foveolate

bearing cavi that are round or nearly so and are separated by distances much greater than their diameter. (syn. pitted. cf. foveate).

fractiflex

bent strongly in alternate directions; decidedly zig-zag. (cf. flexuous)

free

(1) not joined or attached to a similar or different structure. (cf. adnate, connate); (2) of veins: not anastomosing or otherwise joined. (ant. anastomosing).

frond

the photosynthetic organ of ferns, usually consisting of a stipe and lamina, characterized by its often large size and usually highly branched vascular system. (cf. microphyll).

funiform

rope-like and rather thick. (cf. filiform, restiform).

furfuraceous

bearing thin, minute, occasionally amorphous scales, sometimes mixed with hairs, often in a mat. (cf. aspidote, paleaceous, squamous).

gametangium

a structure in which gametes are formed; in ferns, archegonia (female) and antheridia (male). (pl. gametangia).

gamete

a sex cell, in pteridophytes, spermatozoids (male) and ova (female).

gametophyte

an inconspicuous, non-vascular plant that bears gametangia and gametes. In homosporous pteridophytes, they are surficial, thin, chlorophyllous, and filamentous, ribbon-like, or heart-shaped, or somewhat stellate or are subterranean, massive, achlorophyllous, and globular, cylindrical, or branched. In heterosporous pteridophytes, they are much reduced structures borne (and partially developing) within spore walls. (syn. prothallus; cf. sporophyte).

gemma

(1) a markedly abscissent, structurally specialized, often glabrous, asexual propagule found on some sporophytes that detaches and forms a plantlet after dispersal; (2) a markedly abscissent, structurally specialized, paucicellular, asexual propagule found on some gametophytes that detaches and forms a new gametophyte after dispersal (pl. gemmae; adj. gemmiferous; cf. bulbil, bud).

gemmae

plural of gemma.

gemmiferous

bearing one or more gemmae. (n. gemma; n.pl. gemmae; cf. bulbiferous).

gemmulate

bearing bullae that are no higher than wide, slightly to greatly contracted at the base, and with a round apex. (syn. papillate, saccate; cf. aculeate, colliculate, patellate, pustulate).

genus

a rank of taxa intermediate between family and species; the totality of species that are more closely related to one another than they are to any other species of other genera.

glabrescent

becoming glabrous with age.

glabrous

lacking any indument (cf. glandular, hairy, scaly).

gland

a unicellular or paucicellular and one cell wide, filiform, clavate, capitate, or globular epidermal structure containing or secreting resinous or wax-like, often highly coloured substances. (adj. glandular; cf. hair, paraphysis).

glandular

bearing glands. (n. gland; syn. glanduliferous)

glanduliferous

bearing glandular cells. (n. gland; syn. glandular)

glaucous

having the surface very thinly covered and not obscured by a bluish or whitish, wax-like coating, such as the laminae of some Cyathea, Microlepia, Selliguea and Dennstaedtiaceae species (cf. farinose, pruinose).

globular

nearly spherical. (syn. globose; cf. bulbous).

granulate

a modifying term indicating the presence of rather amorphous, minute, grain-like bodies deposited on the surface of the principal ornamentation.

habit

the general aspect of a plant, like arboresent, erect, or pendent.

hair

a unicellular, paucicellular, or multicellular, linear or rarely branched epidermal outgrowth composed of a single elongate cell or of one or more separate files of cells one to several cells long. (adj. hairy; cf. gland, paraphysis).

hairy

having hairs (see hair).

hamate

having a small hook at the apex, usually applied to hairs, especially in Thelypteridaceae. (cf. uncinate).

haploid

a plant that has one set of chromosomes.

hastate

having the shape of an arrowhead, with laterally directed basal lobes. (dim. hastulate; cf. cordate, sagittate).

hastulate

diminutive of hastate.

helicoid

branching repeatedly only on the basiscopic side of the principal axis, and so appearing to have a dichotomously branched rachis, found in a few species of Adiantum. (cf. spiralled).

hemidimorphic

partially dimorphic, either longitudinally or laterally, commonly applied to laminae. (cf. dimorphic, monomorphic, polymorphic).

hemiepiphytic

in pteridophytes, having a long-creeping rhizome or indeterminate rachis so that the plant remains rooted in the ground and climbs tree trunks, as in some species of Lindsaea, Lomariopsis, Lomagramma, Neocheiropteris, Stenochlaena, Teratophyllum and Trichomanes. (n. hemiepiphyte; cf. epiphytic).

hemitelioid

having the form of a shallow saucer, usually firm and fully or partially surrounding the sorus, typical of certain Cyatheaceae.

herbaceous

rather thin and soft in texture.

heterodromous

with the basal portions of the lamina differing in dromy from the apical portions.

heterophyllous

having fronds (in ferns) or microphylls (in lycophytes) of two or more different shapes. (syn. dimorphic, polymorphic).

heterosporous

producing spores of two sizes, each of which develops gametophytes having gametangia of a single sex. (ant. homosporous).

hexaploid

a plant that has six sets of chromosomes.

hippocampiform

seahorse-shaped; shallowly crescent-shaped with rounded ends. (cf. hippocrepiform, reniform, round-reniform, elongate-reniform).

hippocrepiform

horseshoe-shaped; deeply crescent-shaped with rounded ends. (syn. elongate-reniform; cf. hippocampiform, reniform, round-reniform).

hirsute

bearing straight, erect, decidedly stiff and relatively coarse hairs. (dim. hirsutulous; dim.syn. hirtellous).

hirsutulous

diminutive of hirsute. (syn. hirtellous; cf. hirsute).

holotype

the one specimen or other element of the protologue (usually an illustration) used (and usually cited) by the author to prepare the diagnosis or description of a new species.

homonym

a name identical to another name, but based on a different type and usually published by a different author.

homosporous

producing spores of a single size, which develop gametophytes that bear gametangia of one or two sexes. (ant. heterosporous).

horsetail

a common name for any species in the fern genus Equisetum (Equisetaceae).

hyaline

very thin, translucent, and colourless. (cf. scarious).

hydathode

a commonly elevated or sunken, dark or sometimes pale area of the epidermis on the adaxial (top) surface of the lamina that coincides with the end of a vein and exudes water and salts (adj. hydathodous; cf. aerophore, lime dot).

hydathodous

having hydathodes. (n. hydathode; ant. exhydathodous).

hypogeous

growing under the surface of the ground, commonly applied to horizontal rhizomes. (ant. epigeous; cf. subterranean, aerial).

ICBN

the International Code of Botanical Nomenclature.

idioblast

a specialized cell, manifestly different from and scattered among the typical cells of a tissue. (cf. spicular cell).

illegitimate

a validly published name that is contrary to one or more articles of the Code (ICBN), and so must be rejected. (ant. legitimate).

imbricate

overlapping, commonly applied to similar structures like rhizome scales, pinnae, pinnules, or microphylls. (cf. approximate, contiguous, distant).

immature

young; still capable of growth and/or maturation. (cf. mature, senescent).

immersed

within lamina tissue, and so not readily seen upon cursory examination. (cf. complanate, impressed, prominulous, superficial).

imparipinnate

pinnate and terminated by a single pinna similar to the lateral ones. (ant. paripinnate).

impressed

at a level below the surface of lamina tissue, but not completely immersed in it, thus readily seen upon cursory examination. (syn. sunken; cf. complanate, immersed, prominulous, superficial).

incised

deeply, regularly, and sharply cut. (cf. lacerate, laciniate).

included

contained within, as a terminal veinlet within an areola.

incomplete

not fully developed over the usual length or area. (ant. complete).

incorrect

a name that is not correct according to the Code (ICBN). (ant. correct).

incurved

curved acroscopically or adaxially toward an apex or axis. (ant. recurved).

indehiscent

not splitting open or capable of doing so. (ant. dehiscent).

indeterminate

genetically unlimited in growth, and so usually irregular in size or shape; in ferns, often applied to the rachis or other axes, as in Lygodium. (ant. determinate).

indument

the totality of hairs, glands, and scales on a structure. (cf. trichome).

indurated

becoming hard and thick.

indusia

plural of indusium.

indusiate

having indusia. (n. indusium; n.pl. indusia; ant. exindusiate).

indusium

a usually thin, often scale-like, extrorse or rarely introrse epidermal membrane, or a structure subtending the sorus, that partially or fully protects the young sporangia. (pl. indusia; cf coenoindusium, pseudoindusium).

inequilateral

not equal on both sides of an axis. (ant. equilateral).

inermous

lacking narrowly conical, sharp-pointed projections. (ant. aculeate).

inframedial

proximal to the middle; applied to sori that are a little closer to the costa or costule than to the margin. (cf. costal, intramarginal, marginal, medial, supramedial).

internode

the portion of a stem between two nodes, especially in the stems of Equisetum.

interrupted

not continuous; broken by intervening incisions, breaks in venation, or other causes, such as a linear sorus interrupted by incisions in the lamina margin. (ant. continuous).

intramarginal

near the margin, often applied to sori. (cf. costal, inframedial, marginal, medial, supramedial).

intricate

entangled, commonly applied to hairs.

introduced

imported accidentally or intentionally from another place or country. (cf. adventive, escaped, naturalized).

introrse

facing away from or opening away from the margin (toward a central axis) or apex (basiscopically), usually applied to indusia. (ant. extrorse).

invalid

a name that is not valid; i.e. a name that is not published in accordance with the articles of the Code (ICBN) governing the publication of a name. (ant. valid).

invasive

naturalized and capable of spreading rapidly, even to the detriment of native species or vegetation, such as certain species of Blechnum, Cyathea, Lygodium, and Cyclosorus.

involucral

pertaining to an involucre.

involucre

the tubular or bilabiate indusium found in the Hymenophyllaceae and some Dennstaedtiaceae, in which the abaxial and adaxial portions are identical or nearly so.

involute

having the lateral margins rolled adaxially, thus exposing the abaxial surface and covering the adaxial surface. (ant. revolute).

iridescent

reflecting several rainbow-like colors, such as the rhizome scales of some Asplenium and Haplopteris species and the adaxial laminae of some Selaginella and Polypodiaceae.

isodiametric

approximately equal in length and width. (cf. elongate).

isodromous

with the basal pinnules and/or vein groups of the pinnae strictly opposite. (cf. anadromous, catadromous).

isotype

a duplicate of the holotype.

jugate

paired, commonly applied to the number of pairs of lateral pinnae or pairs of pinnules.

juvenile

lacking the most fully developed morphology; in ferns, juveniles may be precociously fertile. (ant. adult).

labia

plural of labium.

labium

a lip; the apical portion of certain involucres. (syn. lip; pl. labia).

lacerate

deeply and irregularly cut, appearing almost torn. (cf. incised, laciniate).

laciniate

cut into narrow lobes, commonly applied to laminae or pinnae. (cf. incised, lacerate).

laesura

the simple, elongate or triradiate, thickened or unthickened scar on the surface of pteridophyte spores. (pl. laesurae; syn. suture).

laesurae

plural of laesura.

lamina

the expanded portion of a frond, usually consisting of a rachis or midrib, other axes or lateral veins, and expanded lamina tissue. (pl. laminae).

laminae

plural of lamina.

laminate

having expanded lamina tissue. (ant. elaminate).

lanceate

spear-shaped, with a long, tapering apex and a nearly truncate base, therefore widest close to or at the base. (cf. lanceolate).

lanceolate

lance-shaped, with a long tapering apex and a short tapering base, therefore widest well above the base. (cf. lanceate).

latent bud

in the Gleicheniaceae and some Dennstaedtiaceae, a bud borne at the apex of an axis that is flanked by two branches; eventually it may break dormancy and elongate, most commonly extending the rachis of the frond. (cf. dormant bud).

lateral

on or near the side. (cf. apical, terminal).

lax

so weak as to be scarcely self-supporting.

lectotype

a specimen chosen by a later author to serve like a holotype from among the syntypes used and cited by the original author.

legitimate

a validly published name, and one that is not contrary to any article of the Code (ICBN). (ant. illegitimate; cf. correct, valid).

leptosporangium

found only in ferns, a thin-walled, thin-pedicelled sporangium bearing usually 64 spores (128--512 in the Osmundaceae and 256 in the Schizaeaceae), and having an annulus. (pl. leptosporangium; adj. leptosporangiate; cf. eusporangium). Leptosporangia are found in all fern families except Equisetaceae, Marattiaceaee, Ophioglossaceae and Psilotaceae.

ligulate

(1) strap-shaped; parallel-sided with a more or less round apex. (cf. spathulate); (2) having a ligule.

ligule

a small, tongue-like, often triangular appendage located near the microphyll base (just distal to the sporangium on the adaxial surface of the microsporophyll); it is persistent in Isoëtes, but caducous in Selaginella. (adj. ligulate; adj.ant. eligulate).

lime dot

a white, crusty exudate from the hydathodes of certain ferns. (cf. hydathode).

linear

long, narrow, and of uniform or nearly uniform width.

lithophytic

growing on rocks. (n. lithophyte; syn. epipetric, saxicolous).

lobate

having shallow sinuses that extend no more than half way from the lobe apex to the axis of the structure that bears the lobes. (n. lobe; syn. lobed; dim. lobulate; cf. pinnate, pinnatifid, pinnatisect).

lobe

a portion of a lamina, pinna, pinnule, or segment that is fully connate and with a shallow sinus on either side that extends no more than half way from the lobe apex to the axis that bears the lobe. (adj. lobate; dim. lobule; dim.adj. lobulate; cf. segment).

lobulate

diminutive of lobate.

lobule

diminutive of lobe.

local

having a very restricted distribution, up to a few square kilometers.

long-creeping rhizome

a rhizome that grows horizontally for at least a few centimeters (usually many more) and that usually has distant stipe bases. (syn. long-repent rhizome; cf. short-creeping rhizome, rhizome).

longitudinal section

a section of an elongate structure, such as a rhizome or stipe, or a planate structure such as a lamina, that is parallel to the principal axis of the structure. If the section passes along and through the principal axis then it can also be called a radial section; if the section is to one side of the principal axis and therefore does not go through that axis then it can also be called a tangential section.

lustrous

reflecting light well because of a smooth surface. (syn. glossy, nitid, shiny; ant. matte).

lycophytes

a group of spore-bearing (seedless) vascular plants that, in terms of their reproductive biology, are similar to ferns but are not closely related to ferns. Lycophytes are the oldest extant group of vascular plants appearing some 50 million years before the first ferns. The group includes quillworts, clubmosses and spikemosses. (cf. monilophytes; fern-allies; pteridophytes).

marcescent

remaining attached long past maturity, but in a withered state. (cf. persistent).

margin

an edge of a flat structure like a lamina or scale (cf. border).

marginal

pertaining to the margin; in sori, borne on the margin rather than on the surface. (ant. superficial; cf. costal, inframedial, intramarginal, medial, supramedial).

marginate

having the central cells of the body different in shape and orientation from the marginal ones. (cf. conform).

matte

not reflecting light well. (syn. dull; ant. lustrous).

mature

incapable of further growth or maturation (especially in determinate structures). (cf. immature, senescent).

medial

(1) in the middle, midway between the base and apex. (cf. distal, proximal); (2) in the middle, in sori, borne midway between the costa or costule and the margin. (cf. costal, inframedial, intramarginal, marginal, supramedial).

megagametophyte

in heterosporous pteridophytes (Azolla, Isoëtes, Marsilea, Pilularia, Regnellidium, Salvinia, and Selaginella), a female gametophyte borne within a megasporangium and bearing one or more archegonia. (cf. microgametophyte).

megasporangium

in heterosporous pteridophytes (Azolla, Isoëtes, Marsilea, Pilularia, Regnellidium, Salvinia, and Selaginella), a sporangium bearing megaspores. (pl. megasporangia; cf. microsporangium).

megaspore

a large spore of the heterosporous pteridophytes (Azolla, Isoëtes, Marsilea, Pilularia, Regnellidium, Salvinia, and Selaginella) that produces a female gametophyte. (cf. microspore).

membranaceous

thin and very flexible. (cf. chartaceous, coriaceous, papyraceous).

meristem

a self-perpetuating, commonly tetrahedral cell or a region of cells that are thin-walled and mitotically dividing and that produce cells which will develop and differentiate into various tissues and structures.

microgametophyte

in heterosporous pteridophytes (Azolla, Isoëtes, Marsilea, Pilularia, Regnellidium, Salvinia, and Selaginella), a male gametophyte borne within a microsporangium and bearing one or more antheridia. (cf. megagametophyte).

microphyll

the photosynthetic organ of the lycophytes, always lacking a stipe, characterized by its usually minute size and unbranched vascular system (a single vein). (cf. frond, megaphyll).

microsporangium

in heterosporous pteridophytes (Azolla, Isoëtes, Marsilea, Pilularia, Regnellidium, Salvinia, and Selaginella), a sporangium bearing microspores. (pl. microsporangia; cf. megasporangium).

microspore

a small spore of the heterosporous pteridophytes (Azolla, Isoëtes, Marsilea, Pilularia, Regnellidium, Salvinia, and Selaginella) that produces a male garnetophyte. (cf. megaspore).

midrib

the major axis of a simple, entire or lobed lamina. (cf. midvein, rachis).

midvein

the central axis of a segment. (cf. midrib).

moniliform

like a string of closely-set, round beads.

monilophytes

ferns. 9,000 - 12,000 species, including horsetails,whisk ferns, and all eusporangiate and leptosporangiateferns. (cf. lycophytes; fern-allies; pteridophytes).

monolete spore

a bilaterally symmetrical spore having a linear, unbranched laesura. (cf. alete spore, trilete spore).

monomorphic

having one shape, commonly applied to fertile versus sterile laminae or portions of laminae. (cf. dimorphic, hemidimorphic, polymorphic).

monophyletic

a group that shares (and includes) a common ancestor and all of its descendants. (syn. natural group; cf. artificial group, paraphyletic, polyphyletic).

mucilaginous

covered with a sticky and gelatinous exudate (such as the very young croziers of some species of Thelypteridaceae and Osmundaceae) or containing such a substance. (n. mucilage).

mucronate

bearing a short, stiff, bristle-like apical prolongation of a midrib, costa, costule or costulet. (n. mucro; dim. mucronulate; cf. apiculate, aristate, cuspidate).

mucronulate

diminutive of mucronate.

multicellular

formed of many cells. (syn. pluricellular; cf. bicellular, paucicellular, unicellular).

multiseriate

disposed in more than two rows; in scales, formed entirely or in part of more than two multicellular rows of cells. (cf. biseriate, uniseriate).

muri

plural of murus.

muricate

having very low, rather sharp protuberances, as the stipe bases of certain Cyatheaceae. (cf. aculeate, tuberculate).

muriform

bearing muri; a general term encompassing many more specialized terms. (n. murus; n.pl. muri; cf. bulliform, caviform, steliform).

murus

a general term for a narrow, elongate, wall-like protuberance; usually applied to spore ornamentation and the basis of many more specialized terms such as cristate, fossulate, pleurate, retate, reticulate, rivulate and rugate. (pl. muri; cf. bulla, cavus, stela).

myrmecophilous

inhabited or capable of being inhabited by ants, usually in modified rhizomes that provide food or shelter, as in Lecanopteris.

native

growing naturally, not as a result of introduction. (syn. indigenous; cf. exotic).

naturalized

originally introduced, but now reproducing and spreading like a native species. (cf. adventive, escaped, introduced).

nectary

in ferns, a tissue, often a small patch or protuberance in the axil of a pinna, that is attractive and nourishing to ants that protect the plant, such as is found in Pteridium.

neotype

a specimen chosen by a later author to replace the holotype, lecototype, or syntypes when these and all their duplicates are missing or destroyed.

nerve

in pteridophytes, a simple or unbranched vein, often a terminal or ultimate vein. (cf. vein, veinlet, venuloid).

nidiform

forming a humus-collecting nest (generally of modified fronds), as in many species of Drynaria and Platycerium. (cf. calathiform).

node

(1) the point on a stem where leaves and branches are borne, especially in Equisetum, or the point on a rhizome where one or more fronds are borne; (2) a discoloured, swollen, or articulate area on the stem of some Selaginella or on the stipe of some ferns, especially Danaea; (3) the attachment points of the sheaths along the stems of Equisetum. (adj. nodose).

nodose

bearing one or more nodes (n. node).

notched

having small transverse gaps; said especially of the ridges on the stems of some Equisetum species and of the cartilaginous margin of the laminae of some Selliguea species.

nude

naked, bare; in the Gleicheniaceae, applied to axes that lack segments.

obconical

cone-shaped, with the apex of the cone basal. (cf. conical).

oblanceolate

gradually tapered toward the base with an obtuse or rounded apex; very narrowly obovate (cf. obovate).

oblique

(1) slanting at an angle to an axis or other structure; (2) unequal-sided, applied to the base or apex of a lamina, pinna or pinnule.

oblong

longer than wide with the long sides parallel or nearly so and the ends abrupt, rather than gradually tapered. (cf. quadrangular).

obovate

the inverse of ovate; ovate with the narrow end toward the base and a round to obtuse apex.

obovoid

a solid structure that is ovate in longitudinal section, with the narrower end basal. (cf. ovoid).

obscure

not easily seen. (ant. obvious).

obsolete

reduced in size or length nearly to the point of elimination, applied especially to stipes. (cf. rudimentary, vestigial).

obtuse

forming an angle of 90° or more with the two sides straight or slightly convex. (cf. acuminate, acute, attenuate).

obvious

easily seen. (ant. obscure).

octoploid

a plant that has eight sets of chromosomes.

odorous

having an odor.

olivaceous

grayish yellow-green.

opaque

not capable of transmitting light. (cf. translucent, transparent).

opposite

having two structures, in ferns usually pinnae, inserted opposite each other at a single point along an axis. (cf. alternate, verticillate).

orbiculate

round in outline. (syn. circular; cf. rounded).

order

a rank of taxa above family and below class; the totality of families that are more closely related to one another than they are to any other families of other orders. Sometimes a single, markedly distinct family also constitutes an order.

ova

plural of ovum.

ovate

having the outline of a longitudinal section of a hen’s egg; similar to elliptical except broadest towards the base, rather than at the middle.

ovoid

a solid structure that is ovate in longitudinal outline, with the wider end basal. (cf. obovoid).

ovum

a non-motile, relatively large, female sex cell (gamete), produced in the archegonium. (pl. ova; syn. egg; cf. spermatozoid).

palea

see paleaceous. (pl. paleae).

paleaceous

bearing thin (in texture), flexible, basifixed or dorsifixed scales. (n. palea; n.pl. paleae; cf. aspidote, furfuraceous, squamous).

paleae

plural of palea.

palmate

having four or more divisions radiating widely from a single point. (cf. digitate, pinnate, ternate).

papillate

(1) bearing minute, low, round protuberances. (n. papilla; n.pl. papillae); (2) a synonym of gemmulate, a specialized term used to describe the surface of spores that are covered with minute papillae. (cf. gemmulate).

papyraceous

having the texture and thickness of rather thin paper. (cf. chartaceous, coriaceous, membranaceous).

paraphyletic

an artificial group that excludes some of the descendants of its common ancestor. (cf. monophyletic, polyphyletic).

paraphysis

a minute, unicellular, paucicellular or multicellular (resembling a simple hair), usually elongate and often glandular structure borne on the soral receptacle, on the sporangium capsule or pedicel, or among the gametangia. (pl. paraphyses; adj. paraphysate; cf. gland, hair, sporangiaster).

paratype

a specimen cited in a protologue that is neither the holotype nor an isotype, nor one of the syntypes if two or more specimens were simultaneously designated as types.

parenchyma

a tissue formed of specialized, thin-walled, living cells with intercelluIar spaces, found in various places in plant bodies. (adj. parenchymatous; cf. sclerenchyma).

paripinnate

pinnate and terminated by a pair of pinnae similar to the lateral ones. (ant. imparipinnate).

patellate

bearing bullae that are no higher than wide, greatly contracted at the base, and round to angular, plate-like, and often slightly concave. (cf. aculeate, colliculate, gemmulate, pustulate).

patent

directed strongly away from the surface of the structure on which it is borne. (cf. appressed, ascending, reflexed).

paucicellular

formed of a few cells. (cf. bicellular, multicellular, unicellular).

pectinate

comb-like; pinnatisect or very deeply pinnatifid with narrow, linear, close-set, segments.

pedate

having the basal basiscopic portions of the basal pinnae more developed and divided, sometimes repeatedly so, than the other portions of the laminae, as in certain Adiantum and Pteris species.

pedicel

(1) the stalk of a sporangium. (cf. capsule, petiolule); (2) the basal cell or cells of a stellate hair or the stalk of a peltate scale or peltate indusium. (syn. stalk; cf. arm, ray).

pedicellate

having a pedicel; usually applied to sporangia, stellate hairs and peltate scales. (syn. pedicelled, stalked; ant. sessile; cf. petiolulate).

peduncle

in Marsilea, the stalk of the sporocarp. (adj. pedunculate)

peltate

attached by a central pedicel, applied to certain indusia and scales and to the sporangiophores of Equisetum. (cf. basifixed, dorsifixed; cf. pseudopeltate).

pendent

hanging down, such as plants of many epiphytic Huperzia species.

pentagonal

5-angled, and so 5-sided, as the lamina outline in some species of Davallia and Cheilanthes. (cf. quadrangular, triangular).

pentaploid

a plant that has five sets of chromosomes.

penultimate

one before the last in a series; between the antepenultimate and last in a series. (cf. antepenultimate).

percurrent

extending to the apex of a simple lamina or simple pinna, applied to midribs and costae.

perispore

the often highly ornamented, outer, sporopollenin layer of the spore wall that is deposited on the exospore by the disintegrating tapetum during spore formation. (syn. perine; cf. endospore, epispore, exospore).

persistent

remaining attached long past maturity in good condition. (cf. caducous, deciduous, marcescent).

petiolulate

having a petiolule; i.e. having a free, usually short portion of the costa, costule or costulet at the base of the pinna, pinnule, or pinnulet that attaches to the axis of the next higher order. (syn. stalked; ant. sessile; cf. pedicellate, stipitate).

petiolule

the short, free, basal portion of a costa, costule, or costulet. (syn. stalk, stipicel; cf. petiole, pedicel, sessile).

phloem

the vascular tissue specialized for transporting photosynthetic products through the plant. (cf. xylem).

phyllopodia

plural of phyllopodium.

phyllopodium

in ferns with articulate stipes, that portion of the stipe proximal to the articulation that remains attached to the rhizome. Phyllopodia are especially prominent in Elaphoglossum and Oleandra but are low and knob-like in Adiantum and many Polypodiaceae. (pl. phyllopodia)

pinnae

plural of pinna.

pinnate

(1) having pinnae that are entire or lobed less than half way to the costae (cf. bipinnate, tripinnate, quadripinnate, lobate, pinnatifid, pinnatisect); (2) having two or more pinnae on each side of a rachis that are not borne from a single point (cf. ternate); (3) branching in which a major free vein gives rise to minor, lateral, free veins.

pinnatifid

incised nearly all the way to the axis (or, ar least, more than half way to the axis), with the segments still partially attached, laterally, to neighbouring segments. (cf. lobate, pinnate, pinnatisect).

pinnatisect

incised all the way to the axis with the segments not contracted at their base and therefore adnate on the axis. (cf. lobate, pinnate, pinnatifid).

pinnule

a petiolulate or sessile division of a pinna that has no lateral attachment to neighbouring divisions. (cf. pinna, pinnulet).

pinnulet

a petiolulate or sessile division of a pinnule that has no lateral attachment to neighbouring divisions. (cf. pinna, pinnule).

planate

flat; level. (syn. plane).

plantlet

a small plant produced by the development of a bulbil or gemma.

pleurate

bearing muri that are long, low, and parallel, and that have sulci between them that are as wide as the muri. (cf. fossulate, rivulate).

polymorphic

having several forms. (cf. dimorphic, hemidimorphic, monomorphic).

polyphyletic

an artificial group that excludes a common ancestor. (cf. monophyletic, paraphyletic).

polyploid

a plant that has more than two sets of chromosomes in cells of the sporophyte or more than one set in cells of the gametophyte.

primary

the first or principal order; applied especially to the veins or axes in a branching system. eg. the main lateral veins arising from the midrib in a simple lamina (as in many Polypodiaceae) or the first lateral branches from the rachis in Gleicheniaceae. (cf. secondary, tertiary, quaternary, quinary).

procumbent

lying on the substrate, but not rooting. (cf. decumbent, prostrate, sarmentose).

produced

more greatly developed than is usual, applied especially to auricles or other parts of laminae or other plane structures. (ant. reduced; cf. prolonged).

proliferous

forming bulbils or plantlets on the laminae, the latter commonly in the axils of distal pinnae, as in Tectaria, or occasionally along the lamina margin, as in Asplenium. (cf. radicant).

prolonged

more greatly extended than is usual, applied especially to axes. (cf. produced).

prominent

noticeable because of contrasting colour and/or raised position with respect to surrounding tissue.

prominulous

slightly raised above the lamina tissue, and so readily seen upon cursory examination, applied to midribs, costae and veins. (cf. complanate, immersed, impressed, superficial).

prostrate

lying on the substrate (a general term). (cf. decumbent, procumbent, sarmentose).

protologue

all the elements associated with a name at its original publication: the description or diagnosis, illustration(s), synonymy and references, specimens cited, and other notes and comments.

protuberance

a structure that bulges or swells out.

proximal

towards or near the base. (cf. basiscopic, distal, medial).

pruinose

having the surface obscured by a rather thick, bluish or whitish, wax-like coating, such as the rhizomes of some Arthromeris and Goniophlebium species. (cf. farinose, glaucous).

pseudodichotomous

not dichotomous but appearing, on cursory examination, to be dichotomous, applied especially to frond complexity and venation. eg. the branching of the fronds of Gleicheniaceae, which bear a latent bud or a dormant bud in each apparent dichotomy; the helicoid branching pattern of some Adiantum species; or a pattern of venation in which the two veins resulting from each fork are free and unequal. (n. pseudodichotomy; syn. falsely dichotomous; cf. dichotomous, pinnate)

pseudoindusium

an introrse, reflexed or revolute, often modified lamina margin that protects young sporangia, especially in the Adiantaceae. (syn. false indusium; cf. coenoindusium, indusium).

pseudopeltate

basifixed with large, overlapping auricles, and so appearing to be peltate, as in the rhizome scales of some Polypodiaceae. (cf. peltate).

psilate

bare; lacking macro- and micro-ornamentation. (syn. plain).

pteridologist

a specialist in pteridology, the study of pteridophytes in a broad sense that includes the ferns (monilophytes) and the more distantly related lycophytes.

pteridology

the study of pteridophytes in a broad sense that includes the ferns (monilophytes) and the more distantly related lycophytes.

pteridophyta

the taxonomic group (Division) that contains all the vascular plants that bear spores instead of seeds: i.e. monilophytes (ferns, now including horsetails and whisk ferns) and lycophytes (quilllworts, clubmosses and spikemosses). In some classifications Pteridophyta is considered a subdivision of Tracheophyta (the Division that contains all vascular plants). (syn. Pteridophytes, "Ferns & Fern Allies").

pteridophytes

in modern usage, a synonym of ferns. In traditional usage, the term was the equivalent of Pteridophyta (or “ferns and fern-allies”) and therefore referred to all the vascular plants that bear spores instead of seeds. i.e. ferns, horsetails and whisk ferns (now all regarded as true ferns) and quillworts, clubmosses and spikemosses.

puberulent

diminutive of pubescent.

puberulous

sparingly pubescent. (cf. pubescent).

pubescent

downy; bearing simple or branched, short, erect, soft hairs. (dim. puberulent; cf. puberulous).

pulvinus

in the Marattiales, a swollen, node-like region at the base of a stipe or costa that loses or gains turgidity under different conditions of hydration and consequently causes fronds or pinnae to collapse or regain their normal position.

puncta

see punctate. (pl. punctae).

punctae

plural of puncta.

punctate

marked with small, round, dark-coloured, glands or bearing sunken, translucent, light-coloured glands visible by transmitted light. (n. puncta; n.pl. punctae).

pustulate

bearing bullae that are distant, broadly attached, no higher than wide, and with an obtuse to round apex. (cf. aculeate, colliculate, gemmulate, patellate).

quadrangular

4-angled, and so 4-sided. (cf. oblong, pentagonal, triangular).

quadrifid

divided into four similar parts, but not nearly to the base. (cf. bifid, bipartite; quadripartite).

quadripartite

divided into four similar parts to or nearly to the base, such as the fronds of Marsilea. (cf. bifid, bipartite, quadrifid).

quadripinnate

divided into pinnae bearing pinnules with the pinnules themselves bipinnate. (syn. 4-pinnate; cf. bipinnate, pinnate, tripinnate).

quaternary

the next order after tertiary, applied especially to the veins or axes in a branching system. (cf. primary, secondary, tertiary, quinary).

quillwort

a common name for any species in the lycophyte genus Isoetes (Isoetaceae).

quinary

the next order after quaternary, applied especially to the veins or axes in a branching system. (cf. primary, secondary, tertiary, quaternary).

rachis

the principal, central axis of a pinnatifid or more compound lamina (cf. midrib, the principal central axis of a simple or lobate frond).

rachises

plural of rachis.

radial

radiating from a central point.

ray

an ultimate branch of a stellate hair or stellately dissected scale. (cf. arm, pedicel).

receptacle

the point or region of the lamina tissue, often thickened and supplied by one or more veins, that produces sporangia and sometimes paraphyses and/or sporangiasters.

recumbent

growing loosely over other vegetation, especially shrubs. (syn. scrambling; cf. scandent).

recurrent

running or pointing towards the midrib or point of origin, usually applied to veins. (cf. excurrent).

recurved

curved basiscopically or abaxially toward a base or axis. (ant. incurved).

reduced

simplified or smaller than is usual. (syn. abbreviated; ant. produced).

reflexed

obliquely directed away from a surface and towards the base of the structure on which it is borne. (syn. deflexed; cf. appressed, ascending, patent).

reniform

kidney-shaped; shallowly crescent-shaped with rounded ends, applied to certain indusia and spores. Note, however, that this term is often loosely applied and that, in fact, most "reniform" indusia are not kidney-shaped. "Reniform" indusia may be almost circular with a shallow notch/short attachment point (i.e. round-reniform) or may be more horseshoe-shaped with a deeper notch/longer attachment point (i.e. elongate-reniform or hippocrepiform). "Reniform" spores may be kidney-shaped but many would be more accurately described as bean-shaped (fabaeform).

repand

irregularly wavy. (cf. crispate, entire, sinuate, undulate).

repent

extending horizontally in or on the soil and rooting throughout, often producing a line of fronds. (syn. reptant; cf. ascending, erect).

restiform

cord-like and rather thin. (cf. filiform, funiform).

retate

bearing muri that are wide and rounded, freely anastomosing, and form short, broad areolae. (syn. rugulate; cf. cristate, reticulate, rugate).

reticula

plural of reticulum. See reticulate.

reticulate

having a branching pattern in the form of a mesh-like or lattice-like net-work. (n. reticulum; n.pl. reticula).

retrorse

directed sharply towards the base, commonly applied to hairs and cilia. (ant. antrorse).

retuse

having a narrow, V-shaped sinus at the round or obtuse apex of a segment, lobe, or tooth. (cf. emarginate).

revolute

having the lateral margins rolled abaxially, thus exposing the adaxial surface and covering the abaxial surface. (ant. involute).

rheophytic

growing in a location that is frequently but not permanently exposed to fast running water, such as on or between rocks along riverbanks or on islands in rivers. (n. rheophyte; cf. amphibious, aquatic, terrestrial )

rhizoid

an elongate, non-vascularized, unicellular or paucicellular structure that serves to anchor the gametophyte and to absorb water and nutrients from the substrate. (cf. root, root hair).

rhizome

in ferns, a usually short (compared to the fronds), scaly or hairy (rarely glandular or glabrous) anchorage structure that bears roots and fronds. Rhizomes may be erect or ascending (and, in either of these cases, trunk-like or not; -- see caudex) or they may be creeping (repent) or climbing (scandent). Creeping rhizomes are often further described as short-creeping (short-repent) or long-creeping (long-repent). (cf. stem).

rhombiform

having the form of a parallelogram, often somewhat to much longer than wide.

rivulate

bearing muri that are long, low, and parallel, with the sulci between them wider than the muri, as in Ceratopteris. (syn. ribbed; cf. fossulate, pleurate).

robust

thick and not easily broken. (syn. stout; ant. delicate).

root

an elongate, vascularized, multicellular structure that serves to anchor the sporophyte and to absorb water and nutrients from the substrate. (adj. rooted; cf. root hair, rhizoid).

root hair

a generally elongate, unicellular, non-vascular outgrowth of a cell of the epidermis of roots that serves to absorb water and nutrients from the substrate. (cf. rhizoid, root).

rooted

having a root.

rosulate

having a circular, radiating cluster of fronds borne horizontally at ground level from a largely subterranean rhizome. (n. rosette).

round

circular in outline (syn. orbiculate; cf. rounded).

rounded

broadly curved to semicircular in outline; usually applied to the shape of an apex or base or the underside of a stipe. (cf. round, circular, orbiculate).

round-reniform

a reniform indusium that is almost circular, compared to a reniform indusium that is more elongate (or horse-shoe shaped). (cf. elongate-reniform).

rudiment*

{definition coming soon}

rudimentary

slightly or partially developed. (cf. obsolete; vestigial).

rugate

bearing muri that are wide, rounded, and non-anastomosing and that do not form areolae. (syn. wrinkled; cf. cristate, retate, reticulate).

rugose

having wrinkles. (dim. rugulose).

rugulose

diminutive of rugose.

saccate

bearing stelae that are higher than wide, bulbous, apparently deflated and collapsed, and widest at the middle. (cf. baculate, clavate, echinate, tuberculate, verrucate).

sagittate

having the shape of an arrowhead with basiscopically directed basal lobes. (cf. cordate, hastate).

sarmenta

plural of sarmentum.

sarmentose

arching above the soil and rooting at intervals, as the rhizomes of certain Lycopodiella and Oleandra species. (cf. decumbent, procumbent; prostrate).

sarmentum

a very thin, recumbent or prostrate root-like or stem-like structure that lacks small, leaf-like appendages but forms new plants along its length or at its tip, as in Nephrolepis. (pl. sarmenta; cf. stolon).

scabrous

rough to the touch. (syn. asperous).

scale

in ferns, a multicellular, usually plane, lanceate or lanceolate to circular, basifixed, dorsifixed, or peltately attached epidermal outgrowth a few to typically many cells wide at the base, but often one cell wide or even hair-like at the apex. Scales are particularly numerous at and near the apices of rhizomes, on the basal parts of stipes and on croziers but they are also found on the laminae of many species. Scale characters are extremely important for fern identification and classification. (adj. scaly; cf. bristle, squamule).

scaly

having scales. (see scale).

scandent

climbing closely on other vegetation, especially tree trunks, as the rhizomes of Stenochlaena (syn. climbing; cf. recumbent).

scarious

very thin and appearing dry. (cf. hyaline).

sclerenchyma

a tissue of very thick-walled cells specialized for support that are dead at maturity, usually associated with vascular tissue in axes or laminae. (adj. sclerenchymatous; cf. parenchyma).

sclerotic

hard or stony.

secondary

the next order after primary; applied especially to the veins or axes in a branching system. eg. secondary veins are the smaller veins or vein-groups that arise from the primary veins, especially the transverse veins linking adjacent primary veins of a simple lamina, as in many Polypodiaceae. (cf. primary, tertiary, quaternary, quinary, transverse).

segment

a portion of a lamina, pinna, or pinnule that is fully adnate and with a deep sinus on each side that extends more than half way from the segment apex to the axis that bears the segment. (cf. lobe).

senescence

the ageing of a plant or part of a plant after maturity, leading eventually to its death. Senescence of fronds or pinnae often, but not always, leads to their abscission.

senescent

grown old; exhibiting changes in biology as a result of ageing after maturity. (cf. immature, mature).

septa

plural of septum.

septate

provided with or divided by septa; in hairs, having thickened and obvious transverse walls between the cells. (n. septum; n.pl. septa; ant. aseptate).

septum

a partition or cross-wall in certain kinds of hairs or hair-like structures. (pl. septa; adj. septate; adj.ant. aseptate).

seriate

disposed in series or rows, applied to a group of similar structures so arranged. (n. series).

serrate

having usually broad teeth on the margin directed acroscopically. (dim. serrulate; cf. crenate, dentate).

serrulate

diminutive of serrate. (cf. crenulate, denticulate).

sessile

lacking a free, basal portion of a stipe, costa, costule or costulet; also applied to organs and structures that lack a pedicel or foot. (ant. pedicellate, petiolulate, stipitate).

seta

a stiff, usually straight, terete, and often dark-coloured hair, found especially on the stipes and laminae of some Grammitidaceae. (cf. cilium)

setae

plural of seta.

setiform

having the form of a seta, a stiff, usually straight, terete, and often dark-coloured hair, found especially on the stipes and laminae of some Grammitidaceae. (n. seta; n.pl. setae; cf. ciliform).

setose

bearing stiff, thin, straight hairs, as on the laminae and stipes of many species or as on the sporangia of some Grammitidaceae and Thelypteridaceae (dim. setulose; cf. ciliate, cincinnate).

setulose

diminutive of setose.

sheath

a tubular structure composed of laterally connate leaves that closely and completely or partially surround a stem, as in Equisetum.

short-creeping rhizome

a rhizome that grows horizontally for a few centimeters at most and that usually has approximate stipe bases. (syn. short-repent rhizome; cf. long-creeping rhizome, rhizome).

shrivelled

curled and wrinkled because of tissue collapse and the loss of moisture, often with age.

simple

not divided, nor compound, nor branched; in laminae, without segments or pinnae; in pinnae, without pinnules. (cf. compound, decompound).

sinuate

distinctly wavy. (cf. crispate, entire, repand, undulate).

sinus

the space between structures, such as adjacent lobes or segments.

skeletonized

having expanded lamina tissue reduced or absent; characteristic of Psilotum, some Hymenophyllaceae and Schizaeaceae, the fertile pinnae of some strongly dimorphic species and the aphlebiae of some species of Cyatheaceae.

solitary

single, and so not near another similar structure.

soral

pertaining to the sorus.

sori

plural of sorus.

soriferous

bearing sori. (n. sorus; n.pl. sori).

sorophore

the gelatinous, sporangium-bearing ring produced by the sporocarp of Marsileaceae during germination.

sorus

a cluster of sporangia having a distinct shape. Maturation of the sporangia may be simple (simultaneous), gradate (sequential), or mixed (a combination of the two foregoing types). (pl. sori; adj. soral).

spathulate

spatula-shaped; narrow at the base and gradually wider distally to a rounded apex. (cf. ligulate).

species

a rank of taxa grouping individuals that typically have a distinct cytology, genetic composition, morphology, and range.

spermatozoid

a motile, relatively small, male sex cell (gamete) produced in the antheridium. (syn. antherozoid, sperm; cf. ovum).

spherical

having the shape of a sphere.

spicular cell

a needle-like, rather thick-walled, idioblast in the epidermis of the lamina, especially in Adiantum and the Vittariaceae. (cf. idioblast).

spikemoss

a common name for any species in the lycophyte genus Selaginella (Sellaginellaceae).

spine

a hard, elongate, sharp-pointed projection, found especially in certain species of Cyatheaceae, Dennstaedtiaceae, and Marattiaceae. Corticinate spines arise from the cortex; squaminate spines are the thickened, central portion of an elongate scale at maturity with the thin marginal portion worn away. (adj. spiny; adj.dim. spinulose; n.dim. spinule).

spinule

diminutive of spine.

spinulose

diminutive of spiny; bearing epidermal projections in the form of short, spine-like teeth along the lamina margin, as the pinnules of most species of Polystichum. (n. spinule).

sporangiaster

an abortive, modified, non-spore-bearing sporangium that presumably serves, like a paraphysis, to protect developing sporangia. (cf. paraphysis).

sporangiophore

a greatly transformed, peltate sporophyll bearing a ring of approximately six sporangia facing the axis of the strobilus of Equisetum. (cf. sporophore).

sporangium

the spore-producing structure of pteridophyta. (pl. sporangia). Sporangia are categorized based on their developmental biology into eusporangia and leptosporangia.

spore

a unicellular, commonly spherical, tetrahedral, reniform or bean-shaped, often elaborately ornamented reproductive structure produced within the sporangium that germinates to form a gametophyte.

sporocarp

in Marsilea, the hard, short- to long-pedunculate, nut-like structure containing the sporangia, apparently a highly modified leaf or leaflet; in Azolla and Salvinia, a thin, short-pedicelled, globular structure containing the sporangia, apparently a modified indusium. (syn. rhizocarp).

sporophore

in pteridophytes, the fertile portions of a hemidimorphic frond, as in the Ophioglossaceae (cf. sporangiophore, trophophore).

sporophyll

(1) in ferns, a frond bearing sporangia; (2) in most lycophytes, a scale-like microphyll subtending a sporangium; (3) in Isoëtes, an elongate microphyll bearing a sporangium within its base. (ant. trophophyll); (4) in Equisetum …? {definition under revision}

sporophyte

in pteridophytes, the conspicuous plant that produces spores. (cf. gametophyte).

spreading

diverging ever more strongly in different directions, and so greatly separated distally one from another, as the labia of the involucres of some Hymenophyllaceae or the scales on some rhizomes and stipes. (syn. flared; cf. divaricate, divergent).

squama

see squamose. (pl. squamae).

squamae

plural of squama.

squamose

bearing thick (in texture), stiff, basifixed or dorsifixed scales. (n. squama; n.pl. squamae; dim. squamulose; cf. aspidote, furfuraceous, paleaceous).

squamule

a minute, reduced, paucicellular scale, found especially on the axes and/or laminae of certain Cyatheaceae. (cf. bristle, scale).

stalked

having a stalk; a general term encompassing many more precise terms such as petiolate, petiolulate, pedicellate, pedicelled, pedunculate, stipitate.

stela

a general term for a radially symmetrical more or less rod-like protuberance (hence higher than wide); usually applied to spore ornamentation and the basis of many more specialized terms such as baculate, clavate, echinate, saccate, tuberculate and verrucate. (pl. stelae; cf. bulla, cavus, murus).

stelae

plural of stela.

stele

the vascular tissue (i.e. one or more vascular bundles composed of xylem and phloem) and associated tisues of a rhizome or other type of stem.

steliform

bearing stelae; a general term encompassing many more specialized terms. (n. stela; n.pl. stelae; cf. bulliform, caviform, muriform).

stellate

star-shaped; applied to hairs and scales. Simple stellate hairs are branched above the base (from the apex of the pedicel) into three or more usually equal rays (see, for example, the hairs on the lamina of Pyrrosia, Platycerium and some Grammitidaceae). Twice-stellate hairs are forked or branched above the base (from the apex of the pedicel) into two or more arms, with each arm branching into three or more usually equal rays (see, for example, the hairs on the stipes and laminae of some Hymenophyllaceae); Stellate scales bear several broad to narrow teeth, usually of unequal size, from a relatively large central point (see, for example, the scales on the lamina of some Asplenium species). (cf. bifurcate, twice-bifurcate).

stem

in lycophytes, a usually long (compared to the microphylls), glabrous (rarely hairy) anchorage structure that bears roots and microphylls. (cf. rhizome).

sterile

in relation to sporophytes: lacking sporangia or viable spores; in relation to gametophytes: lacking gametes and/or gametangia. (ant. fertile).

stiff

rigid and unbending; not flexible or brittle.

stipe

the structure of a frond that connects the base of the lamina to the point of its attachment to the rhizome. (syn. petiole).

stipitate

having a stipe. (syn. petiolate; ant. exstipitate; cf. petiolulate).

stipule

(1) in the Marattiaceae, each one of a pair of lateral, fleshy, starch-bearing, persistent, partially or entirely vascularized outgrowths of the rhizome that clasp the base of the stipe and that are capable of reproducing the plants vegetatively; (2) in the Ophioglossaceae, merely the remnants of the older stipe base that originally enclosed and protected the younger, less developed fronds.

stolon

a very thin, recumbent or prostrate root-like or stem-like structure that bears small, leaf-like appendages and forms new plants along its length or at its tip, as in Selaginella. (syn. sobol; cf. sarmentum).

stoma

a minute, epidermal pore bordered by a pair of relatively large and conspicuous (under the microscope) guard cells and often a usually uniform array of subsidiary cells that differ from the adjacent epidermal cells. (pl. stomata; syn. stomate).

stomata

plural of stoma.

stomium

the area of thin-walled cells of the annulus that split during dehiscence. (cf. annulus).

stramineous

the colour of old straw.

strigose

bearing short, usually fully appressed, straight, coarse and sharp-pointed hairs. (dim. strigulose).

strigulose

diminutive of strigose.

strobilus

in lycophytes and Equisetum, a compact reproductive structure borne at the tips of branches or axes consisting of a central axis bearing closely spaced, spirally arranged sporophylls (in lycophytes) or sporangiophores (in Equisetum). (syn. cone).

submersed

growing entirely under the water. (cf. emersed).

subspecies

a rank of taxa subordinate to species and used for major variants in morphology (such as “incipient species”) that have a discrete range different from that of the species and any other subspecies.

subtended

extended under; growing close to but at a slightly more proximal position on an axis.

subterranean

below ground. (ant. aerial; cf. hypogeous).

subtropical

growing north or south of the tropics in regions with a hot summer and a warm to cool winter (ca. 23°30’–34° N or S Lat.).

subulate

awl-shaped; very narrow and tapered from an expanded base to the apex.

sulcate

having one or more longitudinal grooves, especially on the adaxial side of a stipe, rachis, or costa. (n. sulcus; pl. sulci; cf. bisulcate, canaliculate, trisulcate).

sulci

plural of sulcus.

sulcus

a longitudinal groove, especially on the adaxial side of a stipe, rachis, or costa. (pl. sulci; adj. sulcate).

superficial

on the surface of the lamina, rather than on the margin, applied especially to sorus position (ant. marginal; cf. complanate, immersed, impressed, prominulous).

suprabasal

just above the base, usually applied to pinnae or pinnules.

supramedial

distal to the middle, applied to sori that are a little farther from the costa or costule than the margin. (cf. costal, inframedial, intramarginal, marginal, medial).

sursumcurrent

extending both acroscopically and basiscopically on and adnate to an axis. (cf. decurrent, surcurrent).

symmetric

having a similar outline on both sides of a central axis. (ant. asymmetric).

synangia

plural of synangium.

synangium

a group of sporangia partially to entirely fused laterally, as in Psilotum and some Marattiales. (pl. synangia; cf. coenosorus).

synonym

one of two or more names for the same taxon; if based on the same type (homotypic), they are considered to be nomenclatural synonyms; if based on different types (heterotypic), they are considered to be taxonomic synonyms.

syntype

any one of two or more specimens used and cited by the author to prepare the diagnosis or description, when no holotype was designated. One of the syntypes may be selected to be a lectotype by a later author, but the “rejected” syntypes do not become paratypes, they remain syntypes.

tapetum

the nutritive tissue of the sporangium capsule external to the spores.

taxa

plural of taxon.

taxon

a taxonomic group (at any taxonomic level). (pl. taxa).

temperate

growing in regions (or climates) with a warm summer and cold winter (ca. 34°–58° N or S Lat.).

terete

circular in cross-section, said especially of cylindrical bodies like axes, especially stipes.

terminal

at or pertaining to the apex or tip, commonly applied to simple structures like hairs, scales, or paraphyses. (cf. apical, lateral).

ternate

having three equal or subequal parts borne from a single point at about right angles or nearly so to each other. (cf. digitate, palmate, pinnate).

terrestrial

growing in soil. (cf. aquatic, amphibious).

tertiary

the next order after secondary; applied especially to the veins or axes in a branching system. eg. tertiary veins are the smaller veins that arise from secondary veins. (cf. primary, secondary, quaternary, quinary).

tetrahedral

having the shape of a pyramid with a triangular base, applied to spores.

tetraploid

a plant that has four sets of chromosomes.

thalloid

composed of a flat tissue, and multicellular in two or three dimensions, said of most gametophytes. (ant. filamentous).

tip

see apex.

toothed

having narrowly triangular projections from the margin of a structure. (cf. dentate).

translucent

sufficiently clear to pass light, but not an image. (syn. diaphanous; cf. opaque, transparent).

transparent

sufficiently clear to pass an image. (syn. diaphanous; cf. opaque, translucent).

transverse

(1) a section of an elongate structure, such as a rhizome or stipe, or a planate structure, such as a lamina, that is at a right angle to the principal axis of the structure. (syn. cross-section; cf. longitudinal section); (2) running perpendicularly between a pair of veins of a higher order, applied to veins and venuloids. (syn. cross-vein; cf. secondary).

trapeziform

having the outline of a trapezium, with four unequal sides, none of them parallel.

triangular

3-angled, and so 3-sided, as the laminae of certain Adiantum and Lindsaea species. (cf. pentagonal, quadrangular, trigonal, triquete).

trichome

a general term for any hair-like indument. (cf. indument).

trigonal

triangular in transverse section, with three angles and three convex or concave sides (cf. triangular, triquete).

trilete spore

a radially symmetrical (spherical or tetrahedral) spore having a laesura with three radiating branches. (cf. alete spore, monolete spore).

tripartite

divided into three parts.

tripinnate

divided into pinnae bearing pinnules with the pinnules themselves pinnate. (syn. 3-pinnate; cf. bipinnate, pinnate, quadripinnate).

triploid

a plant that has three sets of chromosomes.

triquete

triangular in transverse section, with three angles and three plane sides (cf. triangular, trigonal).

trisulcate

having three longitudinal grooves, especially on the adaxial side of the stipe, rachis, or costa. (cf. bisulcate, sulcate).

trophophore

the sterile portion of a hemidimorphic frond, as in the Ophioglossaceae. (cf. sporophore).

trophophyll

a vegetative, nutrient-producing frond or microphyll. (ant. sporophyll).

trophopod

the enlarged, persistent, basal portion of a stipe that functions as a storage organ, especially through the cold months, found in some ferns of temperate regions.

tropical

growing in regions with a hot summer and a warm to hot winter (ca. 0°–23°30’ N or S Lat.).

truncate

appearing as if cut off perpendicular to the axis. (cf. abrupt).

tuber

an often scaly, globular to somewhat elongate storage body usually borne on the rhizome or on stolons and sarmenta of a few species of pteridophytes in genera such as Lycopodiella, Selaginella, and Nephrolepis.

tuberculate

(1) bearing stelae that are more than 1 x and less than 1.5 x longer than wide, regular in form (knob-like), and have a rarely truncate or an obtuse to round apex (protuberance). (cf. baculate, clavate, echinate, saccate, verrucate); (2) having short, rounded protuberances, as the stipe bases of certain Cyatheaceae. (cf. aculeate, muricate).

twice-bifurcate

applied to hairs that branch dichotomously twice. i.e. forked above the base (from the apex of the pedicel) into two arms, with each arm forked into two equal or subequal rays. (cf. bifurcate, stellate, twice-stellate).

twice-stellate

applied to some complex stellate hairs that are forked or branched above the base (from the apex of the pedicel) into two or more arms, with each arm branched into three or more usually equal rays. (cf. bifurcate, twice-bifurcate; stellate).

ultimate

the last or smallest order or division. (cf. antepenultimate, penultimate).

uncinate

having hook-like projections. (cf. hamate).

undulate

wavy and not straight in profile. (cf. crispate, entire, repand, sinuate).

uniauriculate

bearing one auricle. (cf. biauriculate).

unicellular

formed of a single cell. (cf. bicellular, multicellular, paucicellular).

unilateral

missing from or different on one side of an axis compared to the other side. (cf. bilateral).

uniseriate

disposed in one row. (cf. biseriate, multiseriate).

valid

a name that is published in accordance with the articles of the Code (ICBN) governing publication; basically one that is effectively published, in the correct form for its rank, with a description or diagnosis or reference to a previously published description or diagnosis, and states a type. (ant. invalid. cf. correct, legitimate).

valve

(1) an involucral lobe, especially in Hymenophyllum and some Dennstaedtiaceae; (2) each half of a sporangium that is divided into halves, as in the Osmundaceae.

variety

a rank of taxa subordinate to species and used for variants in morphology that have a distinct range commonly different from that of the species and from other varieties of the species.

vascular bundle

an elongate strand of conducting cells (xylem tracheids and phloem sieve cells) that serve to conduct water, mineral nutrients, and photosynthetic products. (cf. stele, vascular tissue, vein).

vein

a strand of vascular tissue, especially one in the lamina. (cf. nerve, vascular bundle; veinlet, venuloid).

veinlet

a small vein, usually a subdivision or branch of a vein. (cf. nerve, vein, venuloid).

venation

the totality of veins of a frond, especially their pattern.

ventral

the lower side of a horizontal axis, such as a creeping rhizome, or of a plane non-vascular structure, such as a gametophyte. (ant. dorsal; cf. abaxial).

venuloid

an elongate series of thickened cells appearing to be a vein, but not connected to true veins and not functioning as a vein; found in the laminae of certain Selaginellaceae, Marattiaceae, Adiantaceae and Hymenophyllaceae. (syn. false vein; cf. nerve, vein, veinlet).

vernation

the manner in which the apices of laminae and their subdivisions uncoil or unfold during development to protect their apical meristems.

verrucate

bearing stelae that are more than 1 x and less than 1.5 x longer than wide, irregular in form (wart-like), and have a rarely truncate or an obtuse to round apex (protuberance). (syn. papillose; cf. baculate, clavate, echinate, saccate, tuberculate).

verticillate

having three or more similar structures inserted at a single point along an axis. (n. verticil; syn. whorled; cf. alternate, opposite).

vestigial

occurring in reduced form, compared with a more developed form in related or ancestral species. (cf. obsolete; rudimentary).

whisk-fern

{definition coming soon}

xerophytic

growing in dry places. (n. xerophyte).

xylem

the vascular tissue specialized for the transport of water and minerals throughout the plant. (cf. phloem).

zigzagging

a line, course, or axis that has a series of sharp turns going repeatedly from one direction to another. (n. zigzag).

zygote

a cell formed by the union of a spermatozoid and an ovum, and so the first cell (generally diploid, except in polyploids) of the sporophyte.

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