凸轴蕨 tu zhou jue

Aspidium gracilescens Blume, Enum. Pl. Javae 2: 155. 1828; Dryopteris arisanensis Rosenstock; D. gracilescens (Blume) Kuntze; D. sublaxa Hayata; Lastrea gracilescens (Blume) T. Moore (1858), not Hooker (1857); Nephrodium gracilescens (Blume) Hooker; Thelypteris gracilescens (Blume) Ching.

Plants 40-60 cm tall. Rhizomes short, decumbent or ascending, apices including stipe bases covered with reddish brown lanceolate small scales. Fronds subclustered; stipes 15-30 cm, stramineous or tan, glabrous or with sparse short hairs; laminae narrowly oblong, 20-30 × 6.5-10 cm, pinnate-pinnatifid, apices acuminate and pinnatifid; pinnae 15-18 pairs, subopposite or alternate distally, spreading, proximal 1 or 2 pairs not shortened, tapering to bases, reflexed proximally, sessile; middle ones linear-lanceolate, 4-6.5 × 1-1.4 cm, bases tapering, subtruncate, pinnatifid and reaching narrow wings on both sides of costae, apices acuminate; segments 12-15 pairs, oblique distally, oblong, 4-6 × 2-4 mm, entire or slightly undulate-crenate distally, apices rounded-obtuse. Veinlets evident abaxially, simple, occasionally forked, 5 or 6 pairs per segment, proximal pair arising from above base of costules. Laminae herbaceous, yellowish green when dry, abaxially glabrous or costae adaxially with sparse short hairs, adaxially with dense grayish white short acicular hairs, also veins with sparse similar hairs adaxially. Sori small, orbicular, 3 or 4 pairs per segment, dorsifixed at middle of lateral veinlets, located between costules and margins; indusia small, orbicular-reniform, membranous, brownish, glabrous, persistent or sometimes deciduous.

On soil in dense forests on mountains; 1000-2500 m. Taiwan, Yunnan [Indonesia, S Japan, Malaysia, Philippines; Pacific islands (Polynesia)].