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Buried Treasures: Tasty Tubers of the World
Brooklyn Botanic Garden All-Region Guides
Corms, Rhizomes, Tubers, Tuberous Roots, and Bulbs
Potatoes and other tubers belong to a group of plants called geophytes, which hoard energy in fleshy, underground parts in order to survive unfavorable periods of the year in a semidormant state. The same underground parts fuel rapid growth and reproduction when climatic conditions are right. Cooks and gardeners casually refer to the delicious or merely edible carbohydrate-rich underground storage organs of geophytes as roots and tubers, but botanists prefer a more accurate terminology. They differentiate among corms, rhizomes, tubers, tuberous roots, and bulbs depending on which part of the plant develops into a fleshy storage organ and what its characteristics are, while recognizing that many of these structures exist along a continuum.
They may look like roots, but most of the underground edibles featured in this book are actually modified stems, including yautía, Xanthosoma sagittifolium. Photo: Liza Donatelli
Corms are solid, vertical underground stems that usually have a thin outer covering of papery leaves. Each year after flowering, the existing corm is replaced by a new one that develops on top of it. Jack-in-the-pulpit (Arisaema triphyllum) is a corm.
Rhizomes are swollen stems lying horizontally at or below ground level. Sacred lotus (Nelumbo nucifera) grows from a rhizome.
Tubers are the swollen ends of certain underground stems or roots. Yautía (Xanthosoma sagittifolium) arises from a tuber. Potatoes (cultivars of Solanum tuberosum) are also tubers. Earth chestnut (Lathyrus tuberosus) is a tuberous root.
Bulbs are reduced stems bearing modified fleshy leaves and one or more flower buds. Individual bulbs survive for several years and give rise to new bulbs from their disklike basal stems. Not counting the kitchen staples garlic and onions, true bulbs are not widely eaten and therefore not covered in this book.