East Bay Native Plant Species Alameda and Contra Costa counties are home to many native plant species. We have assembled an incomplete (but growing!) collection of photographs and information about many of these. Search for: Show all species California thistle (Cirsium occidentale var. californicum), is ranked A2 in Alameda and Contra Costa counties. Photo by Dianne Lake.Hall’s bush mallow (Malacothamnus hallii), Lime Ridge Open Space, Walnut Creek. Photo by Cathy Chambers.California horkelia (Horkelia californica). Photo by Toni Corelli (CC-BY-NC 4.0).Shade phacelia (Phacelia nemoralis). Photo by Ken Hickman (CC-BY-NC 4.0).