Maggie's Farm

You beat me to it. Cauliflower is simply a color variation of broccoli.

In fact, cabbage, broccoli, cauliflower, brussels sprouts, kale, collards, kohlrabi, and gai lan are all the same species: Brassica oleracia, the wild mustard or wild cabbage plant. The wild plant is a biennial. The first year, it puts its energy into developing thick and dense leaves, which it uses for energy storage over the winter. The second year, it grows a tall flower spike. So... you can breed it for leaves (collards, kale, gai lan), the leaf buds (cabbage and brussels sprouts), the root (kohlrabi), or the flowers/flower spike (broccoli and cauliflower).