A genus of plants belonging to the mustard family Brassicaceae. The whole family includes a total of 376 different genera and 3,200 different species. 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 (B. oleracea acephala), broccoli (B. oleracea botrytis), cauliflower (B. oleracea cauliflora), head cabbage (B. oleracea capitata), brussel sprouts (B. oleracea gemmifera), and kohlrabi (B. oleracea gongycoides); and Brassica rapa, whose subspecies include pak choi (B. rapa chinensis), Chinese cabbage (B. rapa pekinensis), and turnip (B. rapa rapifera). Also, one subspecies of B. 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 PlantTM, and was developed specifically for scientific study. Additionally, the radish Raphanus sativus is a member of the Brassicaceae family. The full taxonomic classification is kingdom Plantae, division Tracheophyta, subdivision Spermatophyta, class Angiospermae, subclass Dicotyledeonae, order Papaverales, family Brassicaceae.