Mustard is quite a ubiquitous plant, commonly seen along the sides of highways, trails, and backyards of California and most of the rest of North America. As a member of the family Brassicaceae (cabbage family), its flowers have four petals arranged in a cross-like pattern (hence the older name, Cruciferae), and an alternating leaf pattern. Members of the family are quite useful as food sources (cabbage, broccoli, cauliflower, turnips, radishes, watercress, and of course the condiment mustard, made from its seeds), sources of dyes (Isatis tinctoria, or woad, is sometimes used to produce the color indigo), and even as model angiosperms (Arabidopsis thaliana is a common organism of study for botany and genetic students).

Eudicots; Rosids; Brassicales; Brassicaceae; Sinapis alba