Abacopteris repanda

Abacopteris repanda is a fern species in the family Thelypteridaceae, with the specific epithet repanda derived from the Latin repandus meaning bent backward or having a wavy, undulate margin. This epithet typically refers to the margins of the pinnae or pinnules, which in this species display a characteristic wavy or shallowly scalloped outline rather than the deeply lobed or flat margins seen in other Abacopteris species. Undulate margins in fern fronds are a structural feature that can increase the effective surface area for photosynthesis while also influencing how light is captured and reflected in low-light forest understory environments. Abacopteris repanda grows as a terrestrial fern in humid tropical forests, producing fronds from a creeping or ascending rhizome embedded in moist forest soils rich in organic matter. The fronds are pinnate, with the blade divided into pinnae whose margins show the characteristic repand or wavy outline. Venation on the lower surface of pinnae is clearly visible, with veins running from the midrib to the margin in a simple or once-forked pattern typical of the genus. Sori are arranged in rows on the undersurface of fertile pinnae, generally covered by small reniform indusia that dry and curl as the fronds age. The stipe is typically scaly near the base, transitioning to hairy surfaces along the rachis. The species is likely native to humid tropical regions of Asia, Africa, or the Pacific, where it inhabits stream-margin forest, lowland rainforest understory, and shaded rocky slopes. As with all ferns, reproduction is via spores dispersed by wind.