Yellow Nutsedge (Cyperus esculentus L.) is a perennial herbaceous sedge native to the eastern Mediterranean region. It was cultivated in ancient Egypt for its tasty and oil-rich tubers, but the wild form has spread as a weed around the world and adapted to climates from the tropics to the subarctic. It is now considered to be one of the world's most problematic weeds. Yellow Nutsedge reproduces and spreads mainly via tubers.
The cultivated variety of Yellow Nutsedge, Cyperus esculentus var. sativus, has several common names, including Chufa, Tiger Nut, and Rush Nut. Chufa was domesticated in the White Nile region of present-day Sudan. Chufa dates back to at least the fifth millennium BC in the Neolithic age and is thought to be the third most ancient domesticated foodstuff of ancient Egypt after Emmer Wheat (Triticum dicoccon) and Barley (Hordeum vulgare). Remains of this plant dating back to 2400 to 2200 BC have been found in Egyptian tombs. Chufa was spread across North Africa and across southern Europe in the Middle Ages. It is now cultivated around the world on a small scale, including in China, North and South America, Spain, and Australia and is especially popular in West Africa, where it is still consumed as a sweetmeat and side dish, with the "nuts" being eaten raw or roasted. It is grown in the southeastern United States as hog pasture, livestock feed, and a winter food source for Wild Turkeys (Meleagris gallopavo) and waterfowl. In many countries, Chufa is often used as an ingredient in the drink known as horchata. Horchata is a popular soft drink in Spain, made from the milky extract of Chufa tubers sweetened with sugar. Chufa production for this beverage in southeastern Spain was 6,650 metric tons in 1994.
Although worldwide Yellow Nutsedge is not as aggressive and important a weed as Purple Nutsedge (C. rotundus, it is more tolerant of cold and drought than Purple Nutsedge and is therefore found over a wider geographic area. Yellow Nutsedge is now considered a serious weed in Angola, Canada, Kenya, Madagascar, Mozambique, Peru, South Africa, Tanzania, the United States, and Zimbabwe. It is a principle weed problem in Australia, India, Mexico, and Swaziland. It is a common weed in Argentina, Iran, and Portugal and is present as a weed in France and most countries of tropical and subtropical Asia, Africa, and Central and South America. In recent decades, weedy Yellow Nutsedges have also become more widely established across northwestern Europe (Schippers et al. 1995 and references therein). Yellow Nutsedge tubers contaminating gladiolus (Gladiolus spp.) bulbs imported from the North America in the late 1970s are believed to be the source of the weed in the Netherlands (De Vries 1991). Establishment of Yellow Nutsedge as a weed around the world is believed to have occurred through spread of the tubers in contaminated crop seed or rootstocks, ships ballast, and tillage or harvest equipment (Bendixen and Nandihalli 1987).
Yellow Nutsedge is a serious weed in the cultivation of Maize (corn, Zea mays), Sugarcane (Saccharum officinarum), and Potato (Solanum tuberosum), and a principal weed problem in Cotton (Gossypium hirsutum) and Soybean [Glycine max). It is also an important weed in the cultivation of Peanut (Arachis hypogaea), Sugarbeet (Beta vulgaris), many vegetable crops, and turfgrass. Yellow Nutsedge has become a serious weed problem in the eastern and central United States in the last 50 years. It now infests millions of hectares of Corn and Soybean in the United States. It has been a weed pest for many years in the southern United States and is considered one of the 10 most common or troublesome (or both) weeds in Corn, Cotton, Grain Sorghum (Sorghum bicolor), Peanut, Soybeans, and turfgrass in the southern states.
A single plant produces seven to nine tubers at the end of rhizomes. A single tuber has been observed to produce more than 1,900 plants and 6,900 tubers within a year. One Yellow Nutsedge-infested cornfield in Minnesota (United States) was found to have an average of 32 million plants per hectare. The flowers are self-incompatible (obligate out-crossers), but sexual reproduction is rare because the plants mostly reproduce vegetatively.
Although their conclusions have not been universally accepted, Schippers et al. (1995) recognized four varieties of C. esculentus:
(1) var. esculentus, the cultivated form (found in southern Europe; Asia; Africa; and locally in northern areas of North America)
(2) var. macrostachyus (found in southern parts of the United States; in Central America; and in the Netherlands)
(3) var. leptostachyus (found in North and South America and in Western Europe, where it was probably introduced around 1947)
(4) var. heermann (found in southeastern parts of the United States; recently introduced into the Netherlands)
The cultivated variety of Yellow Nutsedge differs from the wild types in several characteristics. The tubers are larger, have higher oil and sugar content, and have no frost tolerance. Tubers of the cultivated variety are distinctly grayish orange as compared with the grayish brown weedy types. The rhizomes are short and most tubers produced directly at the base of the shoots. Flowers are rare in the cultivated variety. The inflorescence is generally smaller, with smaller and fewer spikelets that lack the distinct reddish nerves of the weedy types (De Vries 1991).
Chufa tubers contain around 4% protein, 24% fat, 30% starch, and 16% sucrose (Vaughan and Geisler 1997). Pascual et al. (2000) reviewed the value and uses of Chufa and aspects of its cultivation.
Negbi (1992) reviewed the domestication and evolution of weediness of both Yellow and Purple Nutsedge.
(Bendixen and Nandihalli 1987 and references therein; Schippers et al. 1995 and references therein; Vaughan and Geissler 1997; Defelice 2002 and references therein)