Cauliflower is a vegetable in the Brassica oleracea species, which includes cabbage, Brussels sprouts, broccoli, kale, and kohlrabi. All of these plants are actually variants of the same species, and cauliflower is formally known as Brassica oleracea var. botrytis. Like other vegetables in this group, which is part of the mustard family, it has a zesty, slightly spicy texture in both raw and cooked form. Most stores carry the vegetable at various points in the year.
Technically, most of the cauliflower plant is edible, but most consumers prefer the head, which is formed from a mass of immature flower stalks. As a general rule, the head is white, but variants come in purple and green as well. The crisp green leaves and stalk are also edible, although they require cooking before they can be consumed. Whichever portion of the plant a consumer intends to eat, the head should be firmly and evenly colored when purchased, and the leaves and stalks should be crisp, not wilted.
The name for cauliflower comes from the Latin caulis, which means “stalk,” and floris, for “flower.” Since the term “kale” is also related to caulis, the name could also be translated as kale flower or cabbage flower. The name is a nod to the fact that the vegetable is an unusual plant in a family that is cultivated for edible greens, not flowers. It is of Mediterranean origin, and tends to prefer cool, moist climates. Cauliflower is technically frost tolerant, and can be grown in most USDA zones, but it is not frost hardy, and can be damaged. If the climate is too cold, it will only produce small, partial heads.
Many members of the Botrytis group have been grown throughout Europe for centuries. In the right climate, cauliflower can be coaxed into yielding twice a year, providing a source of nutrition when other plants may not be maturing. However, the plant is notoriously difficult to grow, with finicky temperature requirements, and some gardeners give up on getting it to grow at all, let alone yield twice. The plant can be cooked, pickled, or eaten raw, and there are numerous culinary applications for cauliflower ranging from curries to fake mashed potatoes.
The head of cauliflower is also sometimes called the white curd, or just the curd. At a casual glance, it does resemble curds of milk, since it is lumpy and white. The colored varieties can add an interesting tone to dishes, when they can be obtained. Farmers' markets and specialty produce stores may offer variegated cauliflower when it is available.