Brassica oleracea

Brassica oleracea is a biennial plant that has been cultivated as a cruciferous vegetable since ancient times. Although it is classified as one species, at least seven cultivated varietal groups have emerged from wild cabbage, including cabbage, broccoli, cauliflower, kale, Brussels sprouts, collard greens, and more.

Historical Origins

Various cultivars have evolved from wild cabbage over centuries. Kale varieties date back to the fifth century BCE, while Brussels sprouts only appeared in the 18th century CE.

Many Varieties — One Species

Selective breeding and hybridization have produced a fascinating variety of vegetables. For example, broccoflower is a cross between broccoli and cauliflower, while broccolini blends broccoli with gai lan.

Some mutations, like the striking fractal-patterned romanesco, occur naturally. Romanesco is part of the cauliflower Botrytis cultivar group and has intrigued scientists due to its Fibonacci sequence structure.

And yet, the cultivated varieties and their origins are sometimes disputed. For instance, cauliflower comes in several different varieties including white, orange, purple, and green (often called broccoflower). Similarly, kale comes in many different varieties as well, each of which is often given names that describe the color and texture of its leaves. And let's not forget about white and lavender ornamental kale, which is grown more for its aesthetic value than it palatability. Cabbages also come in varieties of green, white, red, and savoy.

However, Napa cabbage is widely considered to be part of a completely different plant species called Brassica rapa, with several different cultivars of its own. Interestingly enough, napa cabbage is the same species as turnips and bok choy, but that is a subject for another time.