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Gillian Vine looks at a vast vegetable family.
Potatoes are our most widely-grown vegetable. They're easy, producing crops even in old buckets, and cheap - or free if grown from sprouting leftovers from the bottom of the vege bin.
Related to tomatoes and capsicums, potatoes are just one of the 2500 species in the nightshade (Solanaceae) family.
If that sounds a lot, consider the mustard family (Brassicaceae), which has more than 3700 species and innumerable cultivated varieties.
Cabbages, cauliflowers, broccoli, kale, Brussels sprouts and most Asian greens belong here, as do turnips, radishes, horseradish, seakale and kohl rabi.
Collectively known as brassicas, the group was once called Cruciferae because of the four-petalled cross shape of the flowers and are still sometimes termed crucifers. Look at the flowers of candytuft and honesty and you'll understand why they, too, are members of the Brassicaceae clan.
Cabbages are popular with home gardeners. With a choice of large or small varieties, wrinkled or smooth leaves of green or red, that can be eaten raw, cooked or pickled, they are among the most versatile vegetables. They are easier to grow successfully than cauliflowers or Brussels sprouts but, like them and other heading or leafy brassicas, cabbages appreciate rich soil and tolerate fairly fresh manure, although well-rotted horse or sheep poo is better.
If growing Brussels sprouts, be mindful of just how long they take - about five months from seed-sowing to harvesting. For that reason, seedlings should be planted before Christmas.
It seems extraordinary that many of these vegetables started with a single wild cabbage, Brassica oleracea ssp. oleracea, native to southwestern Europe and still occasionally seen on the south coast of England.
Back in Roman times, genetic engineering was unknown but gardeners and farmers two millennia ago understood that saving seed from a plant with desirable characteristics maintained those traits in subsequent generations.
There was - and still is - a downside. Different brassicas, grown side by side, will not stay true to type but begin to revert to their ancestor, which is why commercial seed companies not only keep cabbages well away from cauliflowers but also separate each variety.
As well as ancestry, brassicas have less attractive things in common. One is clubroot, which causes knobby lumps on the roots, yellowing leaves and eventually dead plants. Growing brassicas in a different place each season helps avoid this and modern cultivars are being developed to beat the bug, actually parasitic cells.
The other scourge is the cabbage white, a butterfly apparently brought into New Zealand in 1930 in a shipment of cabbages. (No, don't ask why this easy-to-grow crop was being imported.)
Although parasites have been released to control white butterflies, these newcomers also kill our native red and yellow admiral butterflies. Environmentally friendly, mesh covers do the job nicely for home gardeners, as the butterflies can't get on to the cabbages to lay their eggs.
Strangely, they don't go for my seakale (Crambe maritima), a perennial brassica covered in early spring to blanch the stems as they appear. I lashed out and bought two rhubarb forcing pots for mine but buckets weighed down with bricks work just as well.
In choosing seakale over most other brassicas, I'm in good company, as King George IV loved what his subjects called poor man's asparagus, woofing it down with lots of melted butter, a cabbage for a king.