Hypolepis is a genus of terrestrial ferns in the family Dennstaedtiaceae, order Polypodiales, first described as a genus in 1806. Commonly known as beadferns, the approximately 40–45 accepted species are distributed across tropical and subtropical regions worldwide, with the greatest diversity in the New World, and additional representation in the Old World and on oceanic islands.
Plants in this genus are characterised by long-creeping, slender rhizomes clothed in brown or reddish simple or glandular hairs. The fronds are erect and typically narrow- to broad-triangular in outline, usually 2-pinnate or more finely divided, and often hairy — bearing short bristly or gland-tipped hairs on the surfaces and rachises. Sori are borne near the margins of the frond segments, roughly circular, and either covered by a false indusium (a reflexed flap of the leaf margin) or, in some species, exposed and unprotected.
The genus has a modest presence in Australia, where eight species occur across Queensland, New South Wales, Victoria, and Tasmania. Notable members include Hypolepis tenuifolia (with abundant glandular hairs) and Hypolepis rugosula, recognisable by its broad-triangular fronds up to 115 cm long. Several species formerly placed in Hypolepis have been transferred to related genera; for example, the Australian Hypolepis distans has been moved to Hiya as Hiya distans.
Etymology
The name Hypolepis derives from Greek, meaning "under scale" — a reference to the false indusium formed by the reflexed margin of the frond segment that partially covers the sori from below.
Distribution
Hypolepis occurs across tropical and subtropical regions of the world, with its greatest diversity in the New World (the Americas), and additional species in the Old World and on oceanic islands. In Australia approximately eight species are found in Queensland, New South Wales, Victoria, and Tasmania.
Taxonomy Notes
Hypolepis was described as a genus in 1806 and is placed in the family Dennstaedtiaceae (order Polypodiales). The circumscription of the genus has shifted over time; several Australian and Australasian species have been transferred to segregate genera. The Australian species formerly known as Hypolepis distans was transferred to the genus Hiya as Hiya distans, a move accepted by Field (2020) though not yet incorporated into all regional checklists.
