Ophioglossum costatum R.Br.

Family

Ophioglossaceae

Nomenclature

Ophioglossum costatum R.Br., Prodr. Fl. Nov. Holland.: 163. 1810; Holttum, Rev. Fl. Malaya ed. 2, 2: 629. 1968; Wieffer., Blumea 12: 323. 1964; Tagawa & K.Iwats., Acta Phytotax. Geobot. 25: 16. 1971; Tagawa & K.Iwats., Fl. Thailand 3: 36, f. 3.6–3.7. 1979; Boonkerd & Pollawatn, Pterid. Thailand: 65. 2000.

Ophioglossum fibrosum Schum, Kongl. Dansk. Vid. Nat. 4: 226. 1829; Bedd., Suppl. Ferns Brit. Ind.: 465, t. 289. 1892.

Ophioglossum pedunculosum auct. non Desv.: Clausen, Mem. Torrey Bot. Club 19(2): 140 1938; Holttum, Rev. Fl. Malaya ed. 1, 2: 39, f. 1. 1955 [‘1954’].

Description

Rhizome tuberous, to 1 cm in diameter, 7 mm tall, bearing numerous fleshy roots. Fronds about 18 cm long, 3 on a rhizome; phyllomophore to 30 cm long; trophophyll oblong-lanceolate, acute at apex, narrowly cuneate at base, 4.5–6.5 cm long, 1.3–1.8 cm broad; costae distinct on both surfaces; veins reticulate, main areoles 3 or 4 rows at each side of costae, smaller areoles many, often with included free veinlets; texture rather fleshy, softly herbaceous; sporophyll simple, with stalks of about 10 cm in length; spikes to 4.5 cm long. Sporangia about 0.5 mm in diameter; spores dark, with rather roughly reticulate exospores.

Distribution in Thailand

NORTHERN: Mae Hong Son; EASTERN: Nakhon Ratchasima.

Wider Distribution

Pantropical (?).

Ecology

Terrestrial in mixed deciduous forest at about 400 m alt.

Proposed IUCN Conservation Assessment

Least Concern (LC). This species is widespread and not under any known threat.

Notes

Thai specimens have tuberous rhizomes and roughly reticulate exospores. In African plants referred to this species, however, the exospores have a fine reticulum .

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