Sprouts are seedlings, newborn plants just an inch or so long, and are mainly stem, which elongates to push the first set of leaves aboveground into the sunlight. Of course these infantile stems are tender and not at all fibrous; they’re usually eaten raw or very briefly cooked. Many different plants are germinated to make edible sprouts, but most of them come from a handful of families: the beans (mung and soy, alfalfa), the grains (wheat, corn), the cabbage family (cress, broccoli, mustard, radish), the onion family (onions, chives). Because seedlings are so vulnerable, they’re sometimes protected with strong chemical defenses. In alfalfa sprouts, the defenses include the toxic amino acid canavanine; in broccoli sprouts, the defenses are sulforaphanes, a kind of isothiocyanate that appears to help prevent the development of cancer. Because the wet, warm conditions of sprout production also favor the growth of microbes, raw sprouts are frequently a cause of food poisoning. They should be bought as fresh as possible and kept refrigerated, and are safest when cooked thoroughly.