Stems, Stalks, Tubers, and Rhizomes

Stems and stalks have the main function of conducting nutrients between the root and leaves, and providing support for the aboveground organs. They therefore tend to become fibrous, which is why asparagus and broccoli stems often need to be peeled before cooking, celery and cardoon stalks deveined. The junction between stem and root, which is called the hypocotl, can swell into a storage organ; turnips, celery “root,” and beets are actually part stem, part root. And some plants, including the potato, yam, sunchoke, and ginger, have developed special underground stem structures for nonsexual reproduction: they “clone” themselves by forming a storage organ that can produce its own roots and stem and become an independent—but genetically identical—plant. The common potato and true yam are such swollen underground stem tips called tubers, while the sunchoke and ginger “root” are horizontal underground stems called rhizomes.