The Carquinez Strait region is an area in the northeastern San Francisco Bay Area of California characterized by typical coastal lowland California vegetation dominated by oak woodland, grassland, and coastal scrub. From 1996 through 2010, an inventory of vascular plants was amassed. Of the 795 taxa found within the study area, 13 are ferns, 4 are gymnosperms, and 778 are angiosperms. Of eudicots and monocots, 41% (249) and 46% (79) respectively, are adventives introduced since European colonization. Despite the accessibility of the region and the proximity of institutional herbaria, relatively few collections were made in the study area before the beginning of this study.