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.Shade phacelia (Phacelia nemoralis). Photo by Ken Hickman (CC-BY-NC 4.0).California horkelia (Horkelia californica). Photo by Toni Corelli (CC-BY-NC 4.0).