Hosackia is a genus of flowering plants in the legume family Fabaceae, placed within the tribe Loteae of the subfamily Faboideae. The genus is native to western North America, ranging from British Columbia in Canada south through the western United States to Mexico, with the greatest diversity concentrated in California and the Pacific Coast states.
The taxonomy of Hosackia has a complex history. For much of the nineteenth and twentieth centuries, many of its species were subsumed within a broadly defined genus Lotus, which encompassed both New World and Old World (African and Eurasian) species. A molecular phylogenetic study published in 2000, based on nuclear ribosomal ITS sequences, demonstrated that the American and Old World members of that broadly defined Lotus do not constitute a natural group. When Hosackia is circumscribed narrowly, it is monophyletic. As a result, New World species formerly attributed to Hosackia have variously been redistributed among the related genera Acmispon, Ottleya, and Syrmatium, while Hosackia itself retains a small core of western North American species.
Plants in Hosackia are herbaceous annuals and perennials typical of the legume tribe Loteae, bearing pinnately compound leaves and the characteristic pea-like (papilionaceous) flowers shared across subfamily Faboideae. Species occupy a range of western habitats including stream banks, grasslands, and open slopes. Hosackia oblongifolia, the streambank lotus, is among the better-known members of the genus.
Etymology
The genus name Hosackia honours David Hosack (1769–1835), a prominent American physician, botanist, and horticulturalist based in New York who founded the Elgin Botanic Garden. The name was applied by the Scottish botanist David Don in 1832.
Distribution
Hosackia is native to western North America, from British Columbia, Canada, through the western United States (with highest diversity in California) south to Mexico. Species occupy a variety of habitats including stream banks, open grasslands, and hillside slopes characteristic of the Pacific Coast region.
Taxonomy Notes
Hosackia belongs to tribe Loteae of the legume subfamily Faboideae. Its circumscription has shifted substantially: many species were long placed in a broadly defined Lotus until a 2000 molecular phylogenetic study (nuclear ribosomal ITS data) confirmed that New World and Old World Lotus species are not congeneric. Under a narrowly defined Hosackia, species previously assigned here have been redistributed to Acmispon, Ottleya, and Syrmatium.
