Indigenous

Latin spelunca, cave, grotto, or den; perhaps first collected in such habitats.

Plants medium-sized to large. Rhizomes medium-creeping. Fronds usually large, usually more than 1 m long, occasionally to 3+ m long. Stipes shorter than blades, grooved adaxially, reddish brown or straw-colored, sparsely hairy. Blades 3-pinmite to 3-pinnate-pinnatisect, deltate-elongate, chartaceous, rapidly wilting when stipes are cut; rachises straw-colored to reddish brown, hairs sparse to absent on rachises, costae, and veins and of two types: short (less than 0.5 mm long), stubby, and blunt-tipped, or longer (1-2 mm long), acute-tipped. Ultimate segments lobed to pinnatisect, oblong, obtuse. Veins on abaxial surfaces embedded in and darker than lamina, sparsely hairy to glabrous. Sori supramedial to submarginal. Indusia mostly attached at bases only, open at sides.

Infrequent, occasionally common in spots, especially in the Wai 'anae Mountains of O'ahu, in mesic to wet forests, 480-1,280 m, on Kaua'i, O'ahu, and Hawai'i.

Microlepia speluncae is much less common than M. strigosa in Hawai 'i. It is found from South China, the Himalayas, India, Sri Lanka, the Malay Peninsula, Japan, Taiwan, the Philippines to Polynesia and is the only species in the genus native to Africa. It also extends to the American Tropics, but is probably not native there. It is usually larger than M. strigosa, sometimes much larger.

The fronds are more herbaceous than those of M. strigosa and wilt quickly after picking.

Microlepia speluncae may be distinguished from M. strigosa by its usually larger fronds; often reddish brown stipes and rachises; indusia supramedial to sub-marginal (versus marginal to submarginal in M. strigosa), usually attached mainly at the base; and less prominent, darker, embedded veins.