Hypocalyptus is a small genus of three species of shrubs, subshrubs, and small trees in the family Fabaceae (legume family), order Fabales. It belongs to the subfamily Faboideae and is the sole genus of the tribe Hypocalypteae, making it a monotypic tribe within one of the largest flowering-plant families on earth.
All three species are endemic to the Cape region of South Africa, where they grow in fynbos — the species-rich Mediterranean-climate shrubland of the Cape Floristic Region, one of the world's six plant-diversity hotspots. Within the fynbos biome they occupy forest margins, rocky and sandy slopes, and streambanks, frequently at higher elevations.
The three accepted species are Hypocalyptus sophoroides, Hypocalyptus coluteoides, and Hypocalyptus oxalidifolius. Like most members of Faboideae they bear typical pea-type flowers (papilionate corollas). The genus is part of the extraordinary concentration of endemic legume lineages in the Cape flora.
Distribution
All three species of Hypocalyptus are native to the Cape region of South Africa, growing in fynbos shrubland, forest margins, rocky and sandy habitats, and along streams, often at high elevations.
Ecology
Hypocalyptus species grow in Mediterranean-climate fynbos — one of the world's most biodiverse shrubland types — as well as at forest margins, on rocky and sandy slopes, and along streams in the Cape Floristic Region.
Taxonomy Notes
Hypocalyptus is the sole genus of the tribe Hypocalypteae within the subfamily Faboideae (Fabaceae). GBIF recognises three accepted species. The species were originally described in other genera and later transferred to Hypocalyptus by Baillon and Dahlgren.
