The family is also known as cruciferae because the four petaled flowers of these plants look like crosses. The plants are distributed worldwide and have annual (living one year), biennial (living two years) and perennial (living many years) members.
member species of genus brassica include brassica napus which produces rapeseed or canola oil, brassica nigra which produces yellow mustard, brassica oleracea whose subspecies and strains include kale and collard greens (brassica oleracea acephala), broccoli (brassica oleracea botrytis), cauliflower (brassica oleracea cauliflora), head cabbage (brassica oleracea capitata), brussel sprouts (brassica oleracea gemmifera), and kohlrabi (brassica oleracea gongycoides), and brassica rapa, whose subspecies include pak choi (brassica rapa chinensis), Chinese cabbage (brassica rapa pekinensis), and turnip (brassica rapa rapifera).
also, one subspecies of brassica rapa is used as a model organism to study genetics, molecular biology, plant breeding, cell biology, and physiology, it is called the rapid cycling brassica or RCBr or the Wisconsin fast plant, and was developed specifically for scientific study. Additionally, the radish Raphanus sativus is a member of the Brassicaceae family.