三叉蕨 san cha jue

Polypodium subtriphyllum Hooker & Arnott, Bot. Beechey Voy. 256. 1838; Aspidium hokutense Hayata; A. subtriphyllum (Hooker & Arnott) Hooker; Lenda subtriphylla (Hooker & Arnott) Koidzumi; Nephrodium subtriphyllum (Hooker & Arnott) Baker; Sagenia subtriphylla (Hooker & Arnott) Beddome.

Plants terrestrial, 20-70 cm tall. Rhizome long creeping or ascendant, stout, densely scaly at apex and stipe bases; scales stiff, dark brown, linear-lanceolate, 3-4 mm, membranous, bases rounded or cordate, entire, apices long acuminate. Fronds widely spaced; stipe dark stramineous, 10-40 cm, ca. 3 mm in diam. at base, covered throughout with light brown jointed hairs. Laminae subdimorphic, fertile fronds rather tall but narrowed, pinnate to bipinnatifid at base, deep green when dried, triangular-pentagonal, 10-35 × 10-25 cm, papery, both surfaces glabrescent to densely hairy; rachises stramineous, densely covered with articulate hairs; costae and costules raised on both surfaces, pubescent abaxially; terminal pinna trifurcate or acuminate, base cordate or cuneate to decurrent, terminal lobe ovate-lanceolate, pinnatifid or pinnate-lacerate, lateral lobes opposite, lanceolate, undulate, apices caudate; lateral pinnae 1-3 pairs, opposite, interval 1.5-3 cm, oblique; basal pinnae pinnate, ca. 15 cm, rather large, stalks 1-2 cm, lobes undulate or with orbicular segments; middle pinnae simple, becoming sessile upward, entire, undulate or with orbicular segments, broadly lanceolate, 10-12 cm, bases cordate, apices caudate. Veinlets forming subhexagonal areoles with cross veins, included veinlets forked. Sori small, orbicular, located at coupling veinlets, in irregular rows between adjacent main veins; indusia brown, reniform, small, deciduous.

Dense forests, near streams; below 700 m. Fujian, Guangdong, Guangxi, Guizhou, Hainan, Taiwan, Yunnan [India, Indonesia, Japan (Ryukyu Islands), Myanmar, Sri Lanka, Thailand, Vietnam; Pacific islands (Polynesia)].

A hairier form of Tectaria subtriphylla is found on limestone rocks in Hainan (Changjiang, Danxian, San Ya).