Taylor, W. Carl. 1976. Vascular flora of Jonca Creek, Ste Genevieve County, Missouri. Castanea. 41: 93-118.
Dryopteridaceae
Latin Diagnosis - Ab E. ambiguo (Mett. ex H. Christ) Alston squamis costalibus densioribus brevioribus 0.02-0.05 mm longis (non 0.1-0.2 mm), 1-2 cellularibus (non 3-6-cellularibus), obtusis (non acuminatis), pallidis (non brunneis), erectis (non subappressibus), costis magis valde prominentibus atque squamis petiolaribus latioribus 1.5- 4 mm latis (non 0.5-2 mm) differt.
Species Description - Plants epiphytic; rhizomes compact, erect, 4-10 mm in diameter, densely scaly, the scales hastate, linear-lanceolate, long- acuminate, tortuous, olive-brown to dark brown with translucent cells, 8-15 x 1-2 mm; phyllopodia distinct, 3-5 mm long, usu- ally hidden by the rhizome scales; leaves approximate, 1-2 mm apart, 50-90 x 4-5 cm; petioles ca. 1/4 the sterile leaf length, stramineous to pale reddish brown, sparsely scaly, the scales ovate-lanceolate, entire, flaccid, appressed, deciduous, 2-5 x 1.5-4 mm, brown; blades oblanceolate, chartaceous, apically acuminate, basally decurrent, margins cartilagineous; veins evident, joined by continuous marginal commisural veins, ca. 1.5 mm apart, set at ca. 70' to costae, hydathodes lacking; blades abaxially with scattered, minute, comma-shaped to arachnidoid, orange to red-brown trichomidia, otherwise glabrous; costae on both sides with minute, ca. 0.02-0.05 mm long, 1- to 2(3)-celled, blunt, whitish to tan trichomidia, some are branched and transitional to the laminar trichomidia; fertile leaves unknown.
(Fig. 5 A-E)
Elaphoglossum puberulentum is most closely related to E. ambiguum (Mett. ex H. Christ) Alston, which occurs from Costa Rica to Bolivia. Both species have a similar overall appearance, hair-like scales on the costae, and marginal commisural veins. However, E. puberulentum has denser, shorter (0.02-0.05 mm vs. 0.1-0.2 mm long in E. ambiguum), 1- to 2-celled (vs. 3- to 6-celled), blunt (vs. pointed), pale (vs. brown), erect (vs. subappressed) costal scales, more strongly raised costae, and broader (1.5-4 mm vs. 0.5-2 mm wide) petiole scales. Elaphoglossum ambiguum also appears to be slightly larger overall than E. puberulentum. Both species co-occur in Bolivia without any apparent intergradation. Mesoamerican specimens of E. ambiguum are smaller overall, with even smaller, darker, lanceolate rhizome and petiole scales, shorter petioles, relatively broader leaves, and arachnidoid trichomidia on the blade surfaces, and may represent a further distinct taxon. Elaphoglossum puberulentum is a fairly common species locally at 1450-2200 m in humid montane forest in Bolivia and is likely to occur in Peru. We name this species after the dense, short, hair-like scales on the costae.