desert polygala
Rhinotropis acanthoclada (A.Gray) J.R.Abbott
Desert polygala is a woody member of the milkwort family whose flower-bearing branches finish in thorns. Its small blossoms have two enlarged sepals that form pale wings around the central keel. Flora of North America places it among the thorn-tipped species with cream or greenish wings and a very short or absent beak on the keel. Flora of North America: Rhinotropis identification key
Botanical name
Kew accepts Rhinotropis acanthoclada (A.Gray) J.R.Abbott and lists the catalog name Polygala acanthoclada A.Gray as its homotypic synonym. Kew POWO: Rhinotropis acanthoclada
Recognizing the plant
Short, spreading hairs densely cover the leaves and stems. The stalk of each flower is also hairy and usually shorter than the flower itself; the smaller sepals bear spreading hairs as well. These details help distinguish it from Rhinotropis intermontana, whose flower stalks are normally smooth and longer than the flowers. The blossoms in this group are only about three to five millimetres long, and their sepals fall rather than persisting around the fruit. Flora of North America: Rhinotropis identification key
Native range
Its native range extends from southeastern California through Nevada to southeastern Utah and northern Arizona. It grows in desert or dry shrubland. California records associate it with slopes in shadscale scrub, pinyon–juniper woodland and Joshua tree woodland. Kew POWO: Rhinotropis acanthocladaCalflora: Polygala acanthoclada
Botanical sources
- Kew POWO: Rhinotropis acanthoclada
- Flora of North America: Rhinotropis identification key
- Calflora: Polygala acanthoclada
Reviewed 2026-10-11. Seasonal development varies with location and growing conditions.