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Pleurospermum Hoffmann
Mark F. Watson
Royal Botanic Garden Edinburgh

Perennials or biennial, mostly glabrous some pubescent. Stems erect, terete, sometimes surrounded by fibrous leaf remains at base. Leaves ternately, biternately, pinnately or 2–4-pinnately dissected, rather oblong in outline; ultimate pinnules variously shaped. Umbels compound; rays several or numerous; bracts usually present, sometimes deciduous, often with a membranous white margin; bracteoles present, broad and often showy, usually with a white margin, deciduous. Flowers hermaphrodite. Calyx teeth small or obsolete. Petals white or dark purple, obovate to ovate, almost equal. Stylopodium rounded or broadly conical. Fruit oblong, terete or dorsally subcompressed; mericarps 5-ribbed, narrowly winged.

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Key to species
1 Large robust plants, usually >70cm tall and stems >1.5cm thick at base 2
+ Smaller plants <70cm, but taller specimens (P. dentatum) with stems <1.5cm thick at base 3
2 Margin of pinnules serrate dentate; styles short, to 0.4mm P. angelicoides
+ Margin of pinnules lacerate, deeply pinnatisect; styles longer, c 1.25mm P. benthamii
3 Unbranched fleshy herb with solitary, erect stems 1–2cm broad at base; petiole wings greatly expanded to 4 x 6cm in upper leaves and enveloping the inflorescence P. amabile
+ Stems not fleshy, usually branched above, <1cm broad at base, petioles variously winged but not as above 4
4 Stems, petioles and leaf rachis conspicuously white pubescent P. pilosum
+ Plants glabrous or nearly so; umbels and/or leaf bases sometimes minutely puberulent 5
5 Calyx teeth present >0.5mm, sometimes deciduous in fruit 6
+ Calyx teeth obsolete 7
6 Bracteoles >5mm wide, obovate with acuminate tip, silver-white with a green midrib, margin irregularly serrate; calyx teeth <1mm long, linear-lanceolate P. album
+ Bracteoles <5mm wide, lanceolate–oblanceolate, green with a narrow pale edge, margin usually distinctly papillate; calyx teeth unequal, longest >1mm long, ovate–linear P. hookeri
7 Plants >50cm tall; bracteoles with a broad silver-white margin and dark purple-green midrib P. dentatum
+ Plants usually <30cm; bracteoles pale green, often tinged purple, but without a conspicuously darkened midrib P. apiolens

Pleurospermum angelicoides (DC.) C.B.Clarke
    Pterocyclus angelicoides (DC.) Klotzsch
Nearly glabrous, robust, erect-stemmed perennial to 1.2m or more; stems reddened, stout 1.5–2cm broad, base clothed in the fibrous remains of petioles. Leaves biternately divided, up to 50 x 30cm (including petiole); primary divisions 2–3 pairs up to 20cm long; ultimate pinnules ovate to obovate, 2.5–8 x 2–5cm, usually simple or shallowly 2–3-lobed, acute or rounded, margin serrate-dentate, sparsely pubescent beneath; petiole bases greatly expanded into rounded auricles, 4–9 x 4–5cm, clasping the stem. Umbels 4–15cm across, many-flowered, to 20- or more-rayed; bracts green or whitish, lanceolate 30–40 x 3–7.5mm, deciduous; rays 1.5–6cm in flower, extending to 8–15cm and becoming erect in young fruit; bracteoles lanceolate 10–20 x 2–5mm, white, deciduous; pedicels 2–9mm in flower, 12–18mm in fruit. Calyx teeth absent. Petals purple-pink, obovate, c 2.5 x 1.75mm. Styles short, 0.3–0.4mm, horizontally spreading in fruit. Fruit 8–12 x 3.5–4mm; mericarps slightly compressed, wings c 0.5mm broad.

Bhutan: C—Thimphu district (Barshong); N—Upper Pho Chu district (Gyophu La) and Upper Mangde Chu distirict (Saga La).

Ecology: Meadows and grassy valleys. 3350–4250m. Flowers July–August.

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Pleurospermum benthamii (DC.) C.B.Clarke
    Hymenolaena benthamii DC.
    Pleurospermum davidii Franchet
Very robust, nearly glabrous perennial to 1.5m high or more; stems often tinged red. Leaves to 60 x 19cm (including petiole) , pinnate, pinnules lacerate, deeply pinnatisect, ultimate segments deeply serrate, acuminate; petiole bases winged but not greatly so. Umbels aggregated at tips of branches into dense flowering heads, 10–25-rayed, 3–15cm across in flower; bracts persistent, similar to pinnules of leaves, lacerate-pinnatisect, 1.2–6 x 0.6–3.5cm, margin usually with a yellow-white margin; rays c 2cm long in flower, 5–15cm in fruit; bracteoles ovate-lanceolate, 0.4–3 x 0.3–1cm, serrate, distinctly white margined; pedicels 3–15mm in flower, 8–35mm in fruit. Calyx teeth absent. Petals usually pink with a pale margin or white, ovate acuminate, 2.5–3 x 1.25mm. Styles 1.25mm, diverging in fruit. Fruit ovoid-ellipsoid 6–8 x 2.5–4mm; mericarps rounded on the back, ribs scarcely winged (in Bhutanese specimens).

Bhutan: C—Thimphu district (Pajoding), Punakka district (Dungshinggang) and Bumthang district (Kitiphu); N—Upper Mangde Chu district (Goktang La), Upper Bumthang Chu district (Pangotang) and Upper Kulong Chu district (Me La).
Sikkim: Chakung Chu, Changa, Chola Range, Dik Chhu, Dzongri.

Ecology: Open hillsides, riversides and amongst shrubs. 3400–4300m. Flowers June–August.

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Pleurospermum amabile Craib and W.W.Smith

Vernacular Names: : Tsad, Tsed, Tsey (Bhutanese medicinal names)

Single-stemmed erect plants, 15–50cm tall; stems unbranched, often reddened at base, stout, 1–2cm broad, aromatic when crushed. Leaves 3–4 x pinnately divided, up to 10cm long, including the distinctively winged petiole (lamina of upper leaves shorter than their greatly winged petioles); ultimate segments ovate, c 10 x 7mm, pinnatisect into linear segments 0.5–1mm broad; petioles wings whitish with purple veins, 2.5–4 x 2–6cm. The solitary terminal umbel 5–12cm across, c 25-rayed; rays 3–4cm long, stout c 1.5mm thick; bracts similar to enlarged petioles of upper leaves, tightly enclosing umbel; umbellules c 1.5cm across; bracteoles silvery-white with dark purple midrib, obovate, 6–10 x 3–5mm, abruptly acuminate and toothed above; pedicels c 4mm. Calyx teeth absent. Petals dark purple, c 1.5mm. Stylopodium purple-black; style yellow-green, 0.75mm. Fruit small, oblong, 3–4 x 1.5mm, mericarps ridged but scarcely winged.

Bhutan: C—Thimphu district (Dungtshola, Somana, Wasa La), Tongsa district (Pele La) and Bumthang district (Towli Phu); N—Upper Mo Chu district (Chhew La, Yak La), Upper Pho Chu district (Gyophu La), Upper Bumthang Chu district (Marlung, Tolegong) and Upper Kulong Chu district (Shinge).
Chumbi: Chulong.

Ecology: Screes and exposed alpine turf. 3950–4700m. Flowers July–September.

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Note: This rather rare, but striking high altitude plant is endemic to Bhutan and SE Tibet (south of Lhasa into the Chumbi Valley and across towards the Yunnan/Sichuan border).


Pleurospermum pilosum H.Wolff
    P. apiolens var. nipaulensis Farille & S.B.Malla
Vernacular Name: Tangkuen (Bhutanese medicinal name)

Slightly aromatic, thick tap-rooted perennial 8–30cm high; stem, petiole, leaf rachis, rays and, to a lesser extent, pedicels conspicuously whitish pubescent; stems purplish, leaf remains often clothing the base. Leaves 2–3 x pinnately divided, to 10–25(–50) x 4–5(–12)cm (including petiole); primary divisions 4–6 pairs, 1–3.5cm long; ultimate segments ovate, 3–8 x 2–7mm, pinnatisect, whitish pubescent on veins, especially beneath; petioles winged at base to 6mm wide, wings purplish. Umbels 3–10(–16)cm across, 6–17-rayed; rays 1.2–7(–9)cm long in flower, little elongating in fruit; bracts 1–3, lanceolate, tips sometimes leafy, 1–3cm long, deciduous; umbellules 1.5–2cm across, 20–30-flowered; bracteoles purplish-green (sometimes pale margined), widely obovate, 6–10 x 4–5mm, abruptly acuminate to a short point, denticulate in upper half, pubescent on midrib, persistent; pedicels 2–5mm. Calyx teeth absent. Petals white within, purple-red or greenish on the reverse, c 2 x 1.2mm. Styles short, c 1mm, horizontal in fruit. Fruits oblong 3–6 x 1.5–2mm, mericarps tinged purple, with narrowly winged ridges.

Bhutan: C—Ha district (Chile La), Thimphu district (Somana) and Tongsa district (Padima Tso); N—Upper Mo Chu district (Jari La, Laya, Lingshi Dzong, Nelli La, Zambuthang).
Chumbi: Gautsa to Phari.
Sikkim: Kapup, Thungkarphumoo.

Ecology: Rough alpine pasture, rocky turf slopes. 4000–4500m. Flowers July–October.

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Pleurospermum album H.Wolff

Aromatic perennial 16–70cm tall, nearly glabrous, except for a minute pubescence at base of petioles, rays and veins of bracts, rays sometimes sparsely papillose pubescent; stems 0.5–0.75cm thick at base; tap-root stout, vertical. Leaves finely 3–4 x pinnately divided, lower ones up to 25cm long (including petiole), ultimate pinnules ovate c 6 x 4mm sharply pinnatifid into fine segments; petiole bases of lower leaves narrowly winged, those of upper leaves with widening wings up to 3cm broad, apex becomming more auriculate, and a pronounced white margin. Umbels 3.5–13cm across, 8–10-rayed; rays 1–5cm in flower, extending a little to 7cm in fruit; bracts 5–6, obovate 2–3.5 x 0.8–1.5cm, shortly leafy at apex, margins broad, silvery-white; umbellules 1.5–2 cm diameter; pedicels 5–8mm; bracteoles silvery-white with a green midrib, obovate, c 10 x 5–7mm, apex rounded-truncate to obcordate, acuminate to a point or sometimes trifid, margins irregularly serrulate. Calyx teeth linear-lanceolate, 0.5–0.75mm. Petals white or greenish-white, obovate, c 1 x 0.5mm. Styles 0.75mm, divergent. Mature fruit not known.

Bhutan: C—Thimphu district (Phajoding, Thimphu).
Chumbi: Buetang, Chomp Lhari, Pongling, Tokoo La, Zepla.
Sikkim: Boktak, Dzongri, Kapup, Prek Chu, Thangshing.

Ecology: Amongst boulders by streamsides, open wet grassland. 3950–4900m. Flowers July–September.

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Pleurospermum hookeri C.B.Clarke
    Aulacospermum hookeri (C.B.Clarke) M.A.Farille & S.B.Malla
    Pleurospermum pumilum (DC.)C.B.Clarke
    Pleurospermum wolffianum Fedde
Vernacular Name: Tang-kun-nag-po (Bhutanese medicinal name)

Slender-stemmed perennial, almost glabrous apart from sparsely pubescent or papillose umbels; stems 5–50cm high, stature much affected by the environment; tap-root rather slender. Leaves mostly basal, finely 2–3 x pinnately divided, 8–15(–30) x 2–5cm long (including petiole); ultimate segments ovate,c 5 x 4mm, margin pinnatisect; petiole bases with narrow wings, wings pale green or tinged purple, to 7mm, more prominant in upper stem leaves. Umbels 4–9cm across, 4–10-rayed; rays 1.5–7cm in flower, little elongated in fruit; bracts 1–5, ovate-lanceolate, 1–2(–3)cm, sometimes leafy at apex; umbellules c 1.5cm across; bracteoles green with pale edges, lanceolate to oblanceolate-obovate, 6–15 x 1.5–4mm, distinctly longer than flowers, acuminate, margin usually minutely papillose; pedicels 2–6mm. Calyx teeth unequal, ovate to lanceolate, c 2mm long, becoming reflexed, deciduous. Styles green, c 1mm long. Fruits 3–4 x 1.5mm, mericarps ridged but scarcely winged.

Bhutan: C—Thimphu district (Shodung to Barshong, Thimphu), Punakha district (Dungshelath, Dungshinggong) and Bumthang district (Dhur Chu); N—Upper Mo Chu district (Yale La) and Upper Mangde Chu district (Upper Mangde Chu).
Chumbi: Kalaeree, Sakkurgong.
Sikkim: Chiya Bhanjang, Dzongri, Gochung, Goecha La, Lachung, Lambi, Tangkar La, Yume Samdong.

Ecology: Common in open moist areas, stream beds, etc. 3650–4900m. Flowers May–October.

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Pleurospermum dentatum (DC.) C.B.Clarke

Nearly glabrous, erect perennial 60–100cm tall, bases of petioles and ends of rays and pedicels with dense short strigose pubescence; stems slender, up to 1cm broad at base. Leaves biternately or pinnately divided, to 30cm long or more (including petiole), primary divisions in 4–5 pairs; petiole with narrow wing at base, wings to 6 x 1.5cm, in upper leaves, extending to the first pair of pinnae; ultimate pinnules ovate in outline, 1.2–4(–9) x 1.5–3(–8.5)cm, acute or acuminate, margins serrate or somewhat pinnatifid. Umbels 3–8cm across in flower, 10–20-rayed; rays 1.2–4cm in flower, becoming erect but elongating little in fruit; bracts 3–7, broadly white-margined with a dark midrib extending to an acuminate tip, lanceolate-elliptic, 1.5–2.5 x 0.4–0.7cm, deciduous; umbellules c 1.5cm diameter; pedicels 3–4mm; bracteoles similar to bracts, as long as flowers, 9–15 x 3–5mm, margin sometimes serrulate at apex, persistent. Calyx teeth absent. Petals white, elliptic-obovate, c 1.4 x 1mm, with incurved acuminate tip. Styles 0.9–1.7mm, spreading in fruit. Fruit oblong-ellipsoid, 7–8 x 2–3mm, dorsally compressed, ridges narrowly winged.

Bhutan: C—Ha district (Bangri) and Thimphu district (Cheka, Dungtsho La to Phajoding).
Chumbi: Natu La to Chubitang, Trakarpo.
Sikkim: Dzongri, Kaukola, Namgaythang and Yumthang.
Darjeeling: Singalila.

Ecology: Moist open moorland slopes, disturbed rocky areas. 3050–4300m. Flowers August–September.

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Pleurospermum apiolens C.B.Clarke

Vernacular Name: Tangkuen (Bhutanese medicinal name)

Nearly glabrous erect perennial 15–30(–50)cm tall, only ends of rays and pedicels with a dense short papillose pubescence; stems aromatic, smelling of celery or parsley when crushed; base of stems often clothed with leaf remains. Leaves mostly basal, pinnate 7–25(–40) x 2–4(–11)cm (including petiole); pinnae 4–5 pairs, ovate in outline 1.5–4 x 1.5–4cm coarsely serrate and often ternately lobed; petioles narrowly winged at base, wing often purplish, to 4 x 1cm, upper leaves winged to first pair of pinnae. Umbels 3–9cm across in flower, 5–12-rayed; rays 1.5–4 cm, scarcely elongated in fruit; bracts 4–5 lanceolate, 1.5–2.5 x 0.5–0.7cm, deciduous; umbellules c 15-flowered; bracteoles whitish green, often tinged purple, midrib not darkened, widely obovate, 9–12 x 4–5.5mm, apex rounded-truncate (sometimes obcordate), abruptly acuminate to a short fine point, persistant; pedicels 2–4mm. Calyx teeth absent. Petals as in P. dentatum. Styes short, 0.2–0.5mm. Fruit ovoid 3.5–5 x 2–3mm, mericarps dorsally compressed, narrowly winged.

Bhutan: C—Thimphu district (Pajoding, Tataka); N—Upper Mo Chu district (Laya, Timuzam) and Upper Bumthang Chu district (Tolegang).
Sikkim: Bikbari to Chaunrikhiang, Boktak, Cheungsanthang, Chomnagu, Dzongri, Lachung, Phalut, Pheonp, Tanglu, Tsomgo, Yak La, Yumthang.

Ecology: Amongst shrubs on moraine, scree, alpine turf, forest clearings, etc. 3350-4900m. Flowers August–September.

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