Rhinotropis is a small genus of flowering shrubs and subshrubs in the milkwort family Polygalaceae, order Fabales. The genus was segregated from the large and morphologically diverse genus Polygala by the American botanist J. Richard Abbott in 2011, based on molecular and morphological evidence that supported its recognition as a distinct lineage.
Members of Rhinotropis are native to the arid and semi-arid landscapes of the southwestern United States — including Arizona, California, Colorado, Nevada, New Mexico, Texas, and Utah — and extend southward into Mexico. They are characteristic components of desert scrub, chaparral, and dry woodland communities in this region.
The genus comprises roughly a dozen species, among the better-known being Rhinotropis californica (California milkwort), Rhinotropis cornuta (horned milkwort), Rhinotropis lindheimeri (Lindheimer's milkwort), and Rhinotropis acanthoclada (spiny milkwort). Like other Polygalaceae, species in this genus bear irregular, somewhat orchid-like flowers adapted for insect pollination.
Taxonomy Notes
Rhinotropis was established as a genus distinct from Polygala by J. Richard Abbott in 2011. Prior to that circumscription, its constituent species were placed in Polygala sensu lato. The genus belongs to the family Polygalaceae within the order Fabales.
Distribution
Rhinotropis is native to the southwestern United States, with species occurring in Arizona, California, Colorado, Nevada, New Mexico, Texas, and Utah, and extending into Mexico. The genus is associated with arid and semi-arid habitats across this range.
