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Tasty Tubers and Fabulous Fungi—Unusual Central and South American Vegetables for Your Garden
Plants & Gardens News Volume 18, Number 2 | Summer 2003
by Scott D. Appell
If the Near East was the cradle of human civilization, then Central and South America can be considered its pantry. Crop cultivation may have begun in Mesopotamia hundreds of years earlier than it did in the Tehuacán Valley of Mexico, but the comestible flora of the New World now forms an amazing 75 percent of the globe's cultivated food plants.
Just for reference, here's a short list of edible plants that were domesticated by the Amerindians and have since become commonplace all over the world: corn, beans, squash, potatoes, tomatoes, peppers, pineapples, tomatillos, quinoa, cocoa, vanilla, and avocados. See anything you fancy?
Though there are many unusual cultivars of corn, squash, and other big-name crops worth profiling, I'd like to focus on some New World vegetables that you don't hear too much about. They are fun to grow, pleasing to the eye, and delicious to eat. And cultivating these New World vegetables will give you a deeper insight into the history and ethnobotany of the indigenous peoples of America.
Smallanthus sonchifolia
Yacón
Yacón is a Peruvian and Bolivian cousin of North America's Jerusalem artichoke, and like its boreal relative, it is cultivated for its edible tubers. The plant was highly prized by the Incas, and remnants of it have been found in the coastal archaeological sites at Nazca, Peru, dating from A.D. 500. The tubers are sweet, crunchy, and juicy, and they can be eaten fresh out of hand or stewed. They are wonderful when combined with a salad of raw carrots, raw sweet potatoes, and jicama root (see below), or when sliced with bananas and oranges. The tubers taste sweeter when they are allowed to cure in the sun after harvesting—a process called ckochascca in the Andes. Additionally, the foliage is cooked like spinach and eaten as a vegetable. The plants look very much like Jerusalem artichokes, growing three to nine feet tall and bearing slightly furry and sticky lance-shaped foliage reminiscent of Helianthus tuberosus. The smallish flowers range from bright yellow to orange and are borne in loose terminal heads. Yacón is quite heat tolerant but is very susceptible to cold—several hours at 32°F can kill all plant parts. It is hardy from USDA Zones 10 to 12. Grow it as an annual in northern regions. Plant yacón in light, fertile, well-drained soil, and water it regularly during dry spells.
Oxalis tuberosus
Oca
Oca is an oxalis with edible tubers thought to have evolved in Peru but cultivated from Venezuela to northern Argentina. Although rarely encountered in the U.S., it is a common crop in the Andes, second only to the potato in popularity. Interestingly, it was introduced into New Zealand around 1860, and it has gained culinary popularity there over the last few decades. The plant's tubers look like small, stubby, wrinkled carrots and can be white, yellow, red, or purple, depending on the cultivar. After harvesting, they are sun-dried to increase sweetness and then boiled, roasted, or prepared as pachamanca (with meat roasted in a hole in the ground). The tubers are high in calcium and iron, crisp in texture, and—due to their oxalic acid content—tart in taste. Oca is often called the "potato that does not need sour cream." The plant has an upright growth habit. The leaves are typically trifoliate and reminiscent of those of its cousin the shamrock. Oca is easy to grow and care for. It excels in average soil and full sun. Plant the tubers in spring immediately after the last frost date and harvest in late fall before the first hard freeze. Oxalis tuberosus is hardy to USDA Zone 7.
Tropaeolum tuberosum
Añu
Añu tubers, an important crop among the Andean people of Bolivia, Peru, and Equador.
Añu is a cousin of the more familiar garden nasturtium, Tropaeolum majus. It has been cultivated for its edible tubers since about 5500 B.C. Pre-Incan pictograms portraying the tubers have been found in the mountains of the high Andes, and today añu remains an important crop among the Andean people of Bolivia, Peru, Ecuador, Columbia, and Venezuela. The plant's foliage is typically peltate (disc-shaped, with stalks attached away from leaf margins) like that of its common garden cousin, but its spurred, orange flowers are far narrower in shape. The tubers are boiled for about ten minutes before being served, and they possess some of the peppery taste so relished in the garden nasturtium. The young shoots and flowers are edible as well. Tropaeolum tuberosum is a short-day plant—that is, it only flowers and sets tubers in northern latitudes after the middle of September, when the day length is markedly shorter. Therefore, it must be cultivated as long as possible before frost hits in order to harvest a serviceable crop. Indeed, tubers are best harvested after the plants are killed by the first hard frost. Añu is hardy from Zones 3 to 6. It doesn't perform well in warm, humid climates. The short-day cultivar 'Muru' produces white tubers mottled with purple. The selection 'Ken Aslet', which bears yellowish tubers attractively splashed with crimson, is day-neutral and begins to flower from July onward. Plant tubers or seeds in a loose, moderately fertile, well-drained, friable soil as soon as it has warmed up thoroughly. The plant requires regular watering and a trellis or other support on which to climb.
Pachyrhizus tuberosus
Jícama
The jícama, or yam bean, is quite in vogue now in nouvelle cuisine. It evolved in Mexico and Central America but was brought to the Old World by the Spanish explorers and spread eastward. Currently, it's grown pantropically and is especially favored in Southeast Asia and China. Pachyrhizus tuberosus is a bean species cultivated for its large, crisp, juicy roots. The tan-skinned, white-fleshed, and beet-shaped tubers are eaten raw, stir-fried, boiled, roasted, or braised, and simmered in soups. They are divine when sliced thin and sprinkled with salt, chili pepper, and lemon juice. In Latin America, jícama is also a source of a starch used in custards and puddings. (Take note that all aboveground plant parts are considered toxic, due to their high rotenone content.) A climbing vine that easily grows 10 to 20 feet high in one long season, P. tuberosus has coarse, broadly trifoliate foliage. It is a short-day plant, so it will not produce its lavender or white blossoms—or its fuzzy, lima-bean-shaped pods—until after the middle of September. Southern gardeners will have greater success with the plant than their northern counterparts, as it takes five to nine months to produce harvestable tubers on plants grown from seed. Removing the flowers will result in larger tubers. If left in the ground, the tubers may actually grow five to six feet in length and up to 50 pounds in weight, although roots of this size are far too woody to consume. Jícama prefers full sun and rich, moist soil. It is frost sensitive and hardy to Zone 5.
Manihot esculenta
Cassava, Yuca, Manioc
Like maize, cassava as we know it today does not exist in the wild. It originated in South America as a result of the hybridization and selection of several wild species by the Amerindians of the Amazon Delta. The earliest archaeological records of it are from coastal Peru, dating to about 1000 B.C. Cassava is a shrubby plant that grows up to 12 feet high, with gray to dark gray bark and large, palmately compound leaves. It is cultivated mainly for its large, edible, starchy tubers (though its tender young leaves are also used as a potherb). Primitive, bitter-tasting cultivars contain potentially toxic concentrations of cyanogenic glycosides and therefore must be processed before eating. This involves laborious peeling, grating, washing, and squeezing of the tubers, followed by drying and cooking (and sometimes fermenting). Over the centuries, however, so-called sweet cassava varieties that can be eaten raw have been developed. Most modern commercial cultivars belong to this category. Their smooth-skinned roots can grow up to 3 1/2 feet long and may be eaten boiled, fried, or baked. Full sun or partial shade and regular amounts of moisture are required for cultivation. The soil should be of average fertility but well drained. Cassavas can be grown outdoors year-round in Zones 10 and 11. One cultivar is readily available through mail-order nurseries: Manihot esculenta 'Variegata'. It bears spectacular leaves with creamy-yellow centers and carmine-red petioles (leafstalks).
Ustilago maydis
Huitlacoche, Cuitlacoche
No exploration of Amerindian agriculture would be complete without the mention of huitlacoche, or cuitlacoche. Known as corn smut by North American farmers, Ustilago maydis is a fungus that infects maize kernels and causes them to grow into large, light gray, gall-like structures several inches in diameter. When cooked, these spore-filled swellings turn black and have a delicious earthy flavor. Huitlacoche was cultivated by the Aztecs, and modern Mexican farmers know that infected ears of corn fetch higher prices. The fungus is incorporated into fillings for tamales and enchiladas, and is high in thiamine and niacin. The USDA once aimed (along with U.S. farmers) to eliminate corn smut completely. But ever since savvy restaurateurs started serving it as "corn truffle" in their upscale Mexican eateries, the department has been trying to develop methods for mass-producing the stuff on experimental farms in Pennsylvania and Florida. Huitlacoche spores are not sold commercially, but curious gardeners can encourage its growth on any corn cultivar. (Incidentally, though there are corn-smut-resistant selections, there are no smut-free varieties.) The Aztecs realized that huitlacoche prevailed during times of drought when temperatures ranged from 78°F to 93°F. They encouraged its growth by scratching the cornstalks at soil level with a knife—thereby allowing the water-borne spores easy entrance into the plant.
Nursery Sources:
P.O. Box 772
Port Townsend, WA 98368
360-385-5660
www.abundantlifeseed.org Nichols Garden Nursery
1190 Old Salem Road NE
Albany, OR 97321
800-622-5561
www.nicholsgardennursery.com Seeds of Change
P.O. Box 15700
Santa Fe, NM 87506
888-762-7333
www.seedsofchange.com
8240 Ulmerton Road
Largo, FL 33771-3948
888-613-4446
www.tropilab.com Glasshouse Works
Church Street, P.O. Box 97
Stewart, OH 45778-0097
740-662-2142
www.glasshouseworks.com
Scott D. Appell is a regular contributor to BBG publications and the author of four books, Pansies, Lilies, Tulips, and Orchids. He lives and gardens on St. Croix, in the U.S. Virgin Islands.