Plant of the Week
Latin: Manihot esculenta
Most of us have a vague recollection of food plants from other parts of the world, but we quickly run out of specifics when we go to discuss them. Cassava, for example, is the most important food crop of the New World tropics but few of us gringos would recognize it were we to see it in the store.
Cassava or manioc (Manihot esculenta) is a member of the euphorbia family. It’s a woody shrub with a decidedly erect habit of growth and capable of reaching 10 feet high or more. Plants have a castor bean kind of growth habit with the five- to nine-lobed, foot-wide leaves borne on reddish petioles up to 18 inches long.
The variegated form, called “variegated tapioca,” is not common in the nursery trade but makes a striking summertime addition to the garden. Each leaf center is marked with a field of creamy yellow with a band of green around the edges of the finger-like lobes. Because of the extensive variegation, this cassava seldom gets taller than 4 feet in a growing season. The foliage color holds up well during even the hottest weather.
All parts of cassava contain a high concentration of cyanogenic glucosides (read cyanide) and are poisonous until processed. The slender, starchy, tuberous roots grow at the soil surface and radiate outward. They have a brownish rind and can be 2 to 3 inches thick at the top and 10 to 30 inches long. Roots contain 25 percent to 30 percent starch with most cultivated forms (the “sweet” cassava) having lower levels of cyanide than the more primitive “bitter” types.
Most of us have eaten cassava for years, we just didn’t know it. Tapioca pudding is made from fine dried flakes of cassava starch that coalesce into “pearls” during processing. The starch itself is rather tasteless so tapioca pudding consists primarily of cassava pearls suspended in vanilla pudding.
In August 2007, archeologists at the University of Colorado unearthed a cassava planting at Ceren, a village about 15 miles west of San Salvador buried by a volcanic eruption in 590 AD. This was the first confirmation that the Mayan civilization grew the root crop and helps explain how such large populations were supported in tropical regions. Cassava produces more food energy per given area of land than any other crop other than sugar cane.
Cassava is an easy-to-grow plant that does well in any area with bright light and warm conditions. It will overwinter as far north as zone 8b, but there it freezes back to the ground each year. If will grow in acidic or alkaline soils and is quite drought tolerant, but extremely dry conditions result in small tuberous roots. At least eight months of frost free weather is needed for the plant to produce usable tubers; in poor tropical soils crops may grow three years before they’re harvested.
New plants are started each season by cutting the stems into foot-long lengths. These hardwood cuttings are stripped of any remaining leaves and either stuck into the ground in a vertical position with one node above the ground or placed horizontally in a trench and covered with 3 inches of sandy soil.
By: Gerald Klingaman, retired
Extension Horticulturist - Ornamentals
Extension News - October 12, 2007
The University of Arkansas Division of Agriculture does not maintain lists of retail outlets where these plants can be purchased. Please check your local nursery or other retail outlets to ask about the availability of these plants for your growing area.