May 30, 2021 Malacothamnus hallii Hall's Bush-mallow Hall’s bush mallow (Malacothamnus hallii), Lime Ridge Open Space, Walnut Creek. Photo by Cathy Chambers. California Rare Plant Rank 1B: Plants rare, threatened, or endangered in California and elsewhere Where to see itThis Spring in the East Bay: Dying Acacias and Blooming Wildflowers