Decursive means running down the stem. Pinnata means featherlike. The reference is to the pinnae running down the stem.
Rhizome: long-creeping, branching, black, scales linear, attenuate at apex, to 8 mm long, brown, shining, also hairs.
Frond: 60 cm high by 15 cm wide, deciduous, monomorphic, blade/stipe ratio: 2:1 to 3:1.
Stipe: straw-colored at base, scales tan, lanceolate, below, and pointed hairs on both sides, vascular bundles: 2, crescent-shaped.
Blade: pinnate-pinnatifid or some might say pinnatifid-pinnatifid, narrowly elliptic, herbaceous or papery, light green or grayish green, hairy on both surfaces; scales on every axis of plants, hairs at every portion of plants, simple, forked, acicular, straight or hooked.
Pinnae: 20 to 25 pair, base fused to the winged rachis, the lowest pair (or two lowest) unconnected by wings to the upper ones, diminished, eared, larger pinnae alternate; pinnules round or moderately acute at apex, variously lobed to costae one-third way down; costae not grooved, ovate-lanceolate, light tan to shiny brown scales below; margins crenate at margin; veins free, simple or forked, not reaching the margin.
Sori: round or oblong, many on a segment, medial, between midrib and margin, indusium: absent, sporangia: tan.
Habitat: on rocks in lowlands, low mountains.
Distribution: Japan, southern Korea, southern China, Thailand, Indochina and India .
Hardy to -30°C, USDA Zone 4.
the winged rachis combined with the narrow, elliptic blade is unique
Polypodium decursive-pinnata H. C. Hall
Thelypteris decursive-pinnata (H. C. Hall) Ching
Lastrea decursive-pinnata (H. C. Hall) J. Smith
Dryopteris decursive-pinnata (H. C. Hall)O. Kuntze