梅山铁线蕨 mei shan tie xian jue

Rhizome erect to suberect, short, scales brown with black center, linear, to 4 mm, margins entire. Stipe castaneous to blackish purple, lustrous, 10-20 cm, scales like those on rhizome but uniformly brown; stipe and rachis glabrous or with sparse multicellular hairs; lamina 1-pinnate, linear to lanceolate in outline, 10-50 × 3-6 cm; apex usually prolonged into a whiplike stolon and rooting to form new plantlets, occasionally secondarily prolonged; pinnules 5-20 pairs, basal pinnules largest, reflexed; stalk distinct, usually 3-5 mm, at 60°-90° to rachis; blade mostly dimidiate, usually 20-30 × 10-15 mm, softly herbaceous, both surfaces glabrous, lower margin straight, rounded at apex, upper margin subentire, crisped or lobed for ca. 1/3 of breadth of pinnule, sinuses narrow, lobes rounded to quadrangular, rounded to truncate at subentire or toothed apex; distal pinnules gradually smaller toward apex. Sori 5-16 per pinnule; false indusia 2-3 mm wide, glabrous.

● Margins of secondary forests; ca. 1000 m. Taiwan.

Adiantum meishanianum is known only from a single very small population with less than 100 individuals and was rated in the protologue as critically endangered.