Lepisorus is a genus of ferns in the family Polypodiaceae (order Polypodiales), placed in the subfamily Microsoroideae according to the Pteridophyte Phylogeny Group classification of 2016 (PPG I). The genus comprises approximately 80 species and is predominantly distributed across East Asia, with a handful of species occurring in Africa and one in Hawaii. China alone harbours 49 species, of which 23 are endemic.
Members of Lepisorus are typically epiphytic or epilithic ferns — growing on tree bark or rock surfaces — though a few species are terrestrial. The rhizome creeps along its substrate, covered in distinctive scales that are blackish-brown, opaque or transparent in a lattice-like (clathrate) pattern, and variously shaped from ovate to narrowly lanceolate. Fronds are predominantly simple and undivided, with a short, mostly straw-coloured stipe and a lanceolate to linear lamina that is leathery or papery in texture. Both leaf surfaces are generally hairless, though the underside may bear sparse scales.
The sori — clusters of spore-bearing sporangia — are large and circular to elliptical, arranged in a single row on each side of the midrib. Young sori are covered by distinctive peltate paraphyses (shield-shaped sterile scales) that are often brown at the centre and pale at the margin. Spores are ellipsoid and lack a perispore, with a surface that is mostly rugose or undulate. The genus is cytologically complex, with chromosome counts ranging widely (2n = 39 to 150).
Lepisorus was first described by John Smith in 1846 as a section of the genus Drynaria and was raised to full genus rank by Chinese botanist Ren-Chang Ching in 1933. Molecular phylogenetic studies have since shown that two older genera — Belvisia and Drymotaenium — nest within Lepisorus, and that its superficial resemblance to the unrelated genus Pleopeltis is the result of morphological convergence rather than shared ancestry.
Etymology
The genus name Lepisorus is derived from the Greek lepis (scale) and soros (heap or sorus), a reference to the scaly paraphyses that cover the young sori. In Chinese the genus is known as 瓦韦属 (wǎ wēi shū).
Distribution
Lepisorus is distributed mainly across East Asia, reaching its greatest diversity in China (49 species, 23 endemic). A few species extend to Africa, and one species occurs in Hawaii. Within China the genus spans montane and subtropical zones, with species recorded from the Himalayas (the type species L. nudus was described from Nepal) to Taiwan and the Russian Far East.
Ecology
Most species of Lepisorus grow as epiphytes on tree trunks and branches or as epilithic ferns on rock faces in humid forest environments. Their creeping rhizomes and leathery, often drought-tolerant fronds suit life on exposed bark and stone surfaces where moisture can be intermittent. A few species are terrestrial.
Taxonomy Notes
Lepisorus was first circumscribed by John Smith in 1846 as section Lepisorus of Drynaria, then elevated to genus by Ren-Chang Ching in 1933. Molecular phylogenetic work (e.g., Li Wang et al. 2010) demonstrated that the genera Belvisia and Drymotaenium are nested within Lepisorus and have been formally sunk into it, and that the morphological similarity to Pleopeltis is convergent, not indicative of close relationship. A 2019 study identified Lepisorus as part of a broader "Lepisorus sensu lato" clade within subfamily Microsoroideae (Polypodiaceae). The genus is cytologically complex, with polyploid series extending to 2n ≈ 150.
