Aeschynomene is a genus of flowering plants in the legume family Fabaceae (order Fabales), commonly known as jointvetches. The genus belongs to the tribe Dalbergieae, where it has been placed within an informal monophyletic Dalbergia clade. Plants of the World Online recognises approximately 114 species.
Members of the genus are herbs, shrubs, or small trees, often with sensitive leaves that may fold when touched, a trait shared with other members of the legume family. Many species are aquatic or semi-aquatic, growing along rivers, in flooded fields, and in wetland margins. The genus is distributed across tropical and subtropical regions worldwide, including the Americas, sub-Saharan Africa, and south, southeast, and east Asia, with some species reaching Australia.
The genus as currently circumscribed is paraphyletic. Phylogenetic studies have suggested that the subgenus Ochopodium should be elevated to a distinct genus within Dalbergieae, though additional rearrangements would also be required to make Aeschynomene fully monophyletic. Some species, notably Aeschynomene fluitans, are free-floating aquatics valued in wetland and aquatic garden settings.
Distribution
Aeschynomene is distributed across tropical and subtropical regions of the Americas, sub-Saharan Africa, south, southeast, and east Asia, and Australia. The genus reaches its greatest diversity in warm, seasonally wet habitats, with numerous species occurring in aquatic and semi-aquatic environments such as river margins, floodplains, and seasonally inundated grasslands.
Ecology
Many species in the genus are aquatic or semi-aquatic, growing in flooded fields, along riverbanks, and in wetland margins throughout the tropics. Like other legumes, Aeschynomene species form root nodules with nitrogen-fixing bacteria, contributing to soil fertility in waterlogged habitats. Some floating species, such as Aeschynomene fluitans, have spongy stem tissue that provides buoyancy.
Taxonomy Notes
Aeschynomene is placed in tribe Dalbergieae within the informal, monophyletic Dalbergia clade. The genus as currently circumscribed is paraphyletic; molecular studies suggest that subgenus Ochopodium requires elevation to a separate genus, along with other rearrangements, before Aeschynomene can be considered monophyletic. Plants of the World Online currently accepts approximately 114 species.
