Sticherus pteridellus (Christ) Copel.

Dicranopteris pteridella (Christ) Underw. Bull. Torrey
Club 34: 260. 1907.
Gleichenia pteridella Christ, Bull. Herb. Boiss. II. 6: 284. 1906.
Rhizome undescribed; primary leaf -axis elongate, rigidly ascending, terete, subflexuous, yellowish or dull greenish-brown, glabrate, 2.5-3.5 mm. in diameter, 50 cm. or more long, continuous above, bearing 2 or 3 pairs of spreading primary lateral branches about 12-16 cm. apart; lower primary branches with a continuous (secondary) slender naked axis bearing 2 (or rarely 1] pairs of lateral branches, the first internode 2-3 cm. long, with simple stalked pinnae or once-forked branches at the node above, the second internode elongate (up to 11 cm. long), with small mostly twice-forked lateral branches at the node above, these with mostly short naked internodes and stalked pinnae ; tertiary lateral axes normally abortive, the buds (as in the minor dichotomies) sharply ovate in outline, the scales dark reddish-brown, oblong-ovate, acute, with whitish ciliate margins; upper primary branches usually once-pseudodichotomous, the internode 2.5-4 cm. long, naked, the pinnae stalked (or very rarely the segments descending to the upper part of the internode), 15-22 cm. long, 3.5-4.5 cm. broad, lanceolate, acuminate, pectinate, slightly or not narrowed at the base, the rachis (like the internodes) nearly glabrous or with a few small scattered appressed scales like those of the buds ; segments rigidly herbaceous, close, spreading or slightly decurved, linear from a slightly dilatate base, 1.5-2.4 cm. long, about 3 mm. broad, acutish, dull yellowish-green, much paler below, the margins entire and lightly revolute, the costa prominent below, yellowish, glabrate ; veins about 25-32 pairs, subimmersed below, slightly elevated and conspicuous above, once-forked near the base ; sori inframedial, seated upon the anterior branch, 4-6-sporangiate ; leaf-tissue whitishgranulose below, bearing also minute scattered whitish simple or mostly substellate glandlike scales, these sometimes dark-centered.
Type LOCALITY : Costa Rica.
Distribution : Interior mountain region of Costa Rica, up to 1450 meters elevation.