Elaphoglossum dimorphum (Hook. & Grev.) T.Moore

Description

by: A. Vasco, R.C. Moran, and G. Rouhan

Syntypes: St. Helena. Alex. Walker s.n. (K?), Madras, Dr. Shuter s.n. (K?)

Description: Terrestrial. Rhizome 1-3 mm wide, short-creeping, ascending, scaly, brown, resinous; scales 2-4.5 mm long, lanceolate, brown, entire, the apex acute. Sterile leaves 10-25 cm long, 1-2 mm apart; phyllopodia present, 0.3 cm long; petioles 1/2-1/3 the length of the sterile lamina, brown; scales reduced to resinous dots or sometimes with a few scattered scales, 0.5-1 mm long, lanceolate, light brown; laminae 4-11 x 0.5-2 cm, lanceolate with the margin irregularly lobed, chartaceous, the base evenly or abruptly cuneate, ending well above the phylopodia, the apex acute; veins conspicuous, 1 mm apart, at a angle of 45° with respect to the costa, the apices free; hydathodes absent; lamina scales usually reduced to resinous dots, the unreduced scales minute, less than 0.5 mm long, ovate, appressed, pale whitish, translucent, membranous, entire. Fertile leaves variable in size; petioles tan to brown; laminae lanceolate, the base cuneate, the apex acute.

Distribution: Endemic to St. Helena Island, above 750 m (elevation according to Eastwood et al., 2004b)

Comments: Elaphoglossum dimorphum can be distinguished from the other species occurring in St. Helena Island, by its lobed lamina margin. The world population of Elaphoglossum dimorphum is less than 50 mature individuals, comprising two subpopulations in Diana's Peak National Park (Eastwood et al., 2004b). Evidence from allozymes indicate that E. dimorphum might be of hybrid origin between E. nervosum and E. bifurcatum (Eastwood et al., 2004a), which may explain its rarity. Elaphoglossum dimorphum has been classified as critically endangered by the IUCN (Eastwood, 2004).

Map Distribution

View all records of Elaphoglossum dimorphum (Hook. & Grev.) T.Moore

Objects