Cauliflower is one of several vegetables in the species Brassica oleracea in the genus Brassica, which is in the family Brassicaceae. It is an annual plant that reproduces by seed. Typically, only the head is eaten – the edible white flesh sometimes called "curd" (with a similar appearance to cheese curd). The cauliflower head is composed of a white inflorescence meristem. Cauliflower heads resemble those in broccoli, which differs in having flower buds as the edible portion. Brassica oleracea also includes broccoli, brussels sprouts, cabbage, collard greens, and kale, collectively called "cole" crops, though they are of different cultivar groups.
Raw cauliflower is 92% water, 5% carbohydrates, 2% protein, and contains negligible fat (table). A 100 gram reference amount of raw cauliflower provides 25 calories, and has a high content (20% or more of the Daily Value, DV) of vitamin C (58% DV) and moderate levels of several B vitamins and vitamin K (13-15% DV; table). Contents of dietary minerals are low (7% DV or less).Cauliflower contains several non-nutrient phytochemicals common in the cabbage family that are under preliminary research for their potential properties, including isothiocyanates and glucosinolates. Boiling reduces the levels of cauliflower glucosinolates, while other cooking methods, such as steaming, microwaving, and stir frying, have no significant effect on glucosinolate levels.