Cabbage at heart of a 'family'

Each spring I am amazed at the hundreds of new seed varieties that are developed.

Yet some gardeners are concerned these new plants might be destroying older varieties or that they may not be as nutritious. It's true that plants are changing more rapidly now than ever before through human intervention and breeding programs.

While many of the changes are a part of a planned research strategy, others are due to the simple fact that plants that are more useful or tasty are promoted more heavily.

To put it in perspective, let's examine the history of wild cabbage — one group of cool season crops.

Wild cabbage — or Brassica oleracea plant — is native to the Mediterranean region. Its appearance is similar to a leafy canola plant. Like thousands of other plants, it is a member of the mustard family and as such has a four-petal, cross-shaped flower.

This cabbage genus is one of the oldest vegetable groups known to man and contains many interesting and tasty plants. These vegetable are used worldwide, but all evolved from Brassica oleracea. This family of plants is an excellent example of remarkable crop improvements by simple long-term selection.

Thousands of years ago, people in and around the Mediterranean Sea began growing the first of these ancient "cabbage" plants. Because the leaves were eaten, gardeners naturally selected seeds from plants that grew the largest leaves to propagate the next year's crop. Via selecting one plant over another, small differences were slowly introduced. Over time, the small changes accumulated and produced dramatic results.

Although they look very different, kale, cabbage, kohlrabi, cauliflower, broccoli and Brussels sprouts are all members of Brassica oleracea family.

The differences in these plants came from thousands of years of human cultivation and selective propagation. By the 5th century B.C., the preference for ever-larger leaves led to the development of the vegetable known as kale or Brassica oleracea variety acephala, which means "cabbage of the vegetable garden without a head."

Later, gardeners started growing plants with a tight cluster of tender young leaves in the center of the plant at the top of the stem. Because people preferred plants with a large number of tender leaves packed into the terminal bud, they selected and propagated such plants more frequently. After hundreds of successive generations, plants developed with more and more dense clusters of leaves at the top of the plant.