Tetradymia is a genus of North American shrubs in the groundsel tribe within the sunflower family. Horsebrush is a common name for plants in this genus. • Tetradymia argyraea - CA (Riverside + San Bernardino Cos), AZ (Mohave Co), NV (Clark Co) • Tetradymia axillaris - CA AZ NV UT • Tetradymia canescens - BC WA ID MT WY OR CA NV UT CO AZ NM • Tetradymia comosa - CA NV • Tetradymia filifolia - NM • Tetradymia glabrata - CA NV UT OR ID • Tetradymia nuttallii - NV UT CO WY • Tetradymia spinosa - CA OR NV ID UT MT WY CO NM • Tetradymia stenolepis - CA NV AZ • Tetradymia tetrameres - NV CA (Mono Co) see Lepidospartum Psathyrotes