Microlepia is a genus of terrestrial ferns in the family Dennstaedtiaceae, order Polypodiales, first described by Czech botanist Karel Bořivoj Presl in 1836. The genus comprises approximately 60 accepted species distributed across the tropics and subtropics, with its greatest diversity in Asia — particularly China, which is home to at least 25 species, eight of them endemic.
Plants are medium-sized to large, growing from creeping, siphonostelic rhizomes densely covered in multicellular, grayish stiff hairs but lacking scales. Fronds range from once- to four-times pinnately compound, broadly oblong to ovate-oblong in outline. The stipe base is not articulated and is hairy, with a vertical groove on its upper face. Pinnules or lobes are slightly oblique, with the acroscopic pinnule at the base typically larger than the basiscopic one; surfaces are usually grayish hispid or soft-hairy, most densely so on the rachis and pinna rachis. Veins are free and pinnately branching, with veinlets that do not reach the leaf margin. Sori are round, positioned just inside the margin (intramarginal), each terminating a single veinlet near a notch; the indusium is hemitelioid — fixed at the base and both sides and opening toward the margin. Spores are tetrahedral and glabrous to slightly verrucate.
Beyond China, the genus extends to other parts of Asia, Australia, Africa, the West Indies, Latin America, and various oceanic islands. Molecular studies have suggested that some widely recognised species, such as M. marginata, conceal cryptic species and hybrids, and the genus as a whole is considered in need of taxonomic revision. Well-known members include Microlepia strigosa and Microlepia speluncae, the latter one of the most widespread tropical ferns in the family.
Etymology
The name Microlepia derives from the Greek mikros (small) and lepis (scale), referring to the small, scale-like indusia that cover the sori. The genus was established by Karel Bořivoj Presl in his 1836 work Tentamen Pteridographiae.
Distribution
Microlepia occurs throughout the tropics and subtropics, with the greatest diversity in Asia. China alone hosts at least 25 species, eight of them endemic. The genus is also represented in Australia, Africa, the West Indies, Latin America, and numerous oceanic islands.
Taxonomy Notes
The genus was described by C.Presl in 1836 (Tent. Pterid. 124) and the name Scypholepia J.Smith is treated as a synonym in the Flora of China. Molecular analyses published by Inouye et al. (2004) indicated that M. marginata comprises cryptic species and hybrids, and herbarium collections are frequently inconsistently named; the genus is widely considered to require comprehensive revision.
