Millets

J M J de Wet. Cambridge World History of Food. Editor: Kenneth F Kiple & Kriemhild Conee Ornelas. Volume 1. Cambridge, UK: Cambridge University Press, 2000.

The caryopses of grasses have been harvested as human food since long before the advent of agriculture. Numerous species are still regularly harvested in Africa and Asia during times of scarcity. Among the many hundreds of species harvested as wild cereals, 33 species belonging to 20 genera were domesticated. Their cultivated cereals are dependent on humans for survival because they have lost the ability of natural seed dispersal and have become adapted to cultivated fields.

Cereals are grown on an estimated 730 million hectares and produce about 1,800 million metric tons of grain annually. Wheat, maize, and rice account for at least 80 percent of the annual world cereal production. Barley, sorghum, oats, rye, and pearl millet represent about 19 percent of cereal grains produced, and the remaining 1 percent of production comes from the other 19 grass species that are still grown as human food. These species are minor in terms of total world cereal production, but some are important components of agriculture in Africa and Asia (de Wet 1989).

Cereals that do not belong to the wheat (Triticum), barley (Hordeum), oats (Avena), maize (Zea), or rice (Oryza) genera are commonly referred to as millets (de Wet 1989).

American Millets

The first cultivated cereal in the Americas appears to have been a species of Setaria (Callen 1965, 1967). Archaeological records indicate that this millet was an important source of food in the Valley of Mexico and in northeastern Mexico before the domestication of maize. E. O. Callen (1967) demonstrated a steady increase in size of caryopses of this millet over 1,500 years of use as a cereal. The species, however, never lost the ability of natural seed dispersal. It was displaced by maize as a cereal during the fifth millennium B.C., but later enjoyed a temporary resurgence in importance when it was probably harvested from weed populations that invaded maize fields.

The archaeological record indicates that another native cereal was cultivated in the southeastern United States before the introduction of maize about 3,000 years ago (Wills 1988). Maygrass (Phalaris caroliniana Walt.) was a common component of early agricultural settlements of the region (Chomko and Crawford 1978). It has been proposed that this species was planted by the inhabitants of these early settlements, as they were located well outside the natural range of maygrass (Cowan 1978). Morphological evidence of its domestication, however, is absent.

Two native grass species besides maize, mango (Bromus mango Desv.), and sauwi (Panicum sonorum Beal) were fully domesticated in the Americas by early farming communities. Mango is the only cereal known to have become extinct in historical times (Cruz 1972). Its cultivation was confined to central Chile. In 1782, it was recorded that the Aracanian Indians of that region grew “el Mango,” a kind of rye, and “la Tuca,” a kind of barley (Parodi and Hernandez 1964). Claudio Gay, who visited the province of Chiloe in 1837, collected specimens of this cereal that are currently on file at the herbarium of the Natural History Museum in Paris. He was probably the last botanist to see B. mango grown as a cereal inasmuch as it was replaced during the eighteenth century by wheat and barley introduced to the New World by European settlers.

Mango was grown as a biannual. In the past, farmers allowed animals to graze on mango fields during the first year and harvested it as a cereal at the end of the next summer (Gay 1865). It is surprising that a biannual species should have been domesticated. However, it may have been the only grass in the region that lent itself to domestication. J. Ball (1884) recorded that the people of northwestern Argentina and adjacent territories harvested a species of Bromus as a wild cereal.

Sauwi, another native American, was extensively grown along the flood plains of the Rio Grande until the late nineteenth century (Palmer 1871; Elsasser 1979). It was sown as soon as the water receded (Kelly 1977). Today sauwi is grown only by the Warihios of the southeastern Sonora and adjacent Chihuahua of Mexico (Nabhan and de Wet 1984).

The species Panicum sonorum occurs as part of the natural vegetation along the western escarpment of the Sierras from southern Arizona to Honduras. It is an aggressive colonizer and often occurs in large continuous populations. It is relished by grazing animals and harvested as a wild fodder by farmers in the Mexican states of Chihuahua and Sonora. Cultivated sauwi differs conspicuously from wild P. sonorum in having larger spikelets that tardily disarticulate from inflorescences at maturity. Sauwi was probably domesticated by farmers who also grew other crops. It is found in an archaeological context associated with beans and cucurbits (Kaemlein 1936). This cereal is a potentially promising fodder crop in semiarid regions of Africa and Asia.

Wild rice of North America (Zizania aquatica L.) is the only grass species domesticated as a cereal by present-day plant breeders. Early European explorers were impressed by the extensive use of this wild grass. In 1778, Jonathan Carver reported that wild rice was the most valuable of all the native wild food plants of the country (Carver 1778: 522-5). It had been harvested as a cereal from rivers and lakes in the northern states and adjacent Canada since long before recorded history (Coville and Coves 1894; Jenks 1900; Larsen 1939). Charred remains of wild rice caryopses found in threshing pits date from well before contact with Europeans (Ford and Brose 1975). Wild rice is now harvested from wild populations on a commercial scale, and it is also grown in paddies because such harvests cannot meet demand.

Wild rice was only domesticated very recently (de Wet and Oelke 1979). But the species does not readily lend itself to domestication: Caryopses rapidly lose viability after harvest if not stored underwater or in mud, and the species does not thrive in stagnant water. Therefore, domestication involved a combination of selection for spikelets that persisted on the panicle at maturity and the development of a cropping system that took advantage of natural adaptations of the species.

Wild rice is now successfully grown on a commercial scale. Paddies are constructed so that a minimum water depth of 15 centimeters (cm) can be maintained. These are flooded and seeded in early spring. Germination is rapid, and water level is maintained until the crop matures. Fields are drained, and the crop is mechanically harvested.

African Millets

The Near Eastern cereals, wheat and barley, have been cultivated in North Africa since at least the late fifth millennium B.C. (Clark 1976). However, these temperate cereals are poorly adapted for cultivation in the tropics south of the Sahara, where eight tropical African grass species were locally domesticated.

Sorghum (Sorghum bicolor [L.] Moench) is the most important native African cereal. It is grown on some 50 million hectares and produces up to 80 million metric tons of grain annually, primarily for human food or animal feed. Wild sorghum is widely distributed south of the Sahara in the Sudanian climatic zone, which receives 600 to 800 millimeters (mm) of annual rainfall and extends into the wetter Guinean zone. It became a cultivated cereal at least 5,000 years ago (Connah 1967: 25; de Wet 1978; Wendorf et al. 1992).

Pearl millet (Pennisetum glaucum [L.] R. Br.), also called bulrush millet, is the second most important native African cereal. It is cultivated across the arid and semiarid tropics of Africa and Asia where no other cereal consistently produces a harvest because of low annual rainfall and high soil temperatures. Pearl millet is grown on about 14 million hectares in Africa and 11 million hectares in India and Pakistan. In areas where annual rainfall exceeds 600 mm in the African and Indian tropics, pearl millet is usually replaced by sorghum as a dry land crop, and in locations where annual rainfall is over 1,200 mm, finger millet or maize becomes the cereal of choice.

The species Penisetum glaucum (pearl millet) is morphologically complex. O. Stapf and C. E. Hubbard (1934) recognized 13 cultivated, 15 weed, and 6 wild taxa of this complex species.W. D. Clayton (1972), by contrast, recognized 2 wild species, 2 weed taxa, and 1 cultivated complex. J. N. Brunken (1977), however, demonstrated that these taxa are conspecific. Wild taxa are often difficult to distinguish from weed taxa, which, in turn, grade morphologically into cultivated taxa. Agricultural weeds, known as shibras in West Africa, often resemble cultivated pearl millet, except for their natural seed dispersal.The involucres of cultivated pearl millet do not disarticulate at maturity. Shibras are common in the cultivated pearl millet zone of West Africa and the Sudan. They also occur in southern Angola and Namibia.

Wild pearl millet taxa occur extensively from coastal Senegal and Mauritania to northeastern Ethiopia in the Sahelo-Sudanian (350 to 600 mm annual rainfall) zone.They also extend into the Sudanian (600 to 800 mm) bioclimatic zone and are found along the foothills of mountains in the Central Sahara. Wild taxa are aggressive colonizers of disturbed habitats and are often weedy around villages.

Cultivated pearl millet is genetically and morphologically variable (Brunken 1977; Clement 1985; Marchais and Tostain 1985). Inflorescences range in shape from cylindrical to broadly elliptic and in length from 5 to 200 centimeters. Large inflorescences are commonly produced on plants with single culms, whereas small- to medium-sized inflorescences are produced on plants that tiller.

Four races of pearl millet were recognized by Brunken, J. M. J. de Wet, and J. R. Harlan (1977).

  1. Race typhoides is grown across the range of pearl millet cultivation and is characterized by obovate caryopses that are obtuse and terete in cross section. Inflorescences are variable in length, but usually several times longer than wide, and more or less cylindrical in shape.
  2. Race nigritarum differs from typhoides, primarily, in having obovate caryopses that are angular in cross section. It is the dominant pearl millet of the eastern Sahel from Sudan to Nigeria.
  3. The principal pearl millet in the Sahel west of Nigeria is race globosum. It has large, globose caryopses, and commonly large, candle-shaped inflorescences.
  4. Race leonis is the pearl millet common to Sierra Leone, Senegal, and Mauritania. It has oblanceolate caryopses with the apex acute.

Pearl millet could have been domesticated anywhere along the southern fringes of the Sahara (Harlan 1971). Botanical evidence indicates that the Pennisetum violaceum complex, as recognized by Clayton (1972), is the progenitor of domesticated pearl millet.

J. D. Clark (1976) suggested that cereal cultivation spread from the Near East to North Africa during the fifth millennium B.C. and subsequently became established across North Africa. With the onset of the present dry phase in North Africa, cultivation of these Mediterranean cereals was eventually confined to the coastal belt, and those farmers forced south by the expanding desert domesticated native grasses as cereals (Clark 1964).

Along the southern fringes of the expanding desert, the most abundant tropical grass species that invites domestication is P. violaceum. Its colonizing ability gives rise to large populations that facilitate its harvesting as a wild cereal. Indeed, P. J. Munson (1976) presented archaeological evidence of such harvesting along the southwestern fringes of the Sahara dating as far back as 3,000 years, and O. Davies (1968) reported archaeological remains of cultivated pearl millet in northern Ghana dated at about the same time. Cultivated pearl millet eventually reached India as a cereal some 2,500 years ago (Rao et al. 1963).

Wild pearl millet is a typical desert grass. It produces large numbers of caryopses that can withstand heat and drought and remain dormant in the soil until conditions become favorable for germination. Caryopses germinate rapidly after the first good rains of the season, and seedlings quickly extend roots into the subsurface soil layers. Plants tiller profusely, go dormant under heat or drought stress, and produce new tillers when conditions become favorable for growth and reproduction. The strategy for survival in such a harsh environment is opportunism with respect to moisture availability and tolerance with respect to high temperature.

Cultivated pearl millet retains these adaptations. It grows and develops rapidly under conditions of adequate soil moisture and elevated temperatures, and thus can take advantage of a short growing season, to survive short periods of severe drought, and to resume growth when water becomes available again. Comparisons among genotypes indicate that differences in time of flowering under stress are the major component of yield differences among cultivars (Bidinger, Mahalakshmi, and Rao 1987). This suggests that the high degree of variability in time to flower among landrace populations is the result of natural selection for early flowering and, thus, escape from drought in dry years, and farmer selection for late flowering plants with large inflorescences in wet years (de Wet, Peacock, and Bidinger 1991). These adaptations make pearl millet the dominant cereal in the Sahelo-Sudanian zone of Africa and in semiarid regions of Zambia, Zimbabwe, Namibia,Angola, northwestern India, and adjacent Pakistan.

Finger millet (Eleusine coracana [L.] Gaertn.) is another native African cereal that was introduced into India during the first millennium B.C. (Vishnu-Mittre 1968). Finger millet is cultivated in wetter and cooler seasonal rainfall zones of southern Africa on about 1 million hectares and is a major cereal in the Lake Victoria region, particularly in eastern Uganda. In India, finger millet is grown on about 3 million hectares from Uttar Pradesh to Bihar and south to Tamil Nadu and Karnataka, with the states of Andhra Pradesh, Karnataka, and Tamil Nadu the major producers of this cereal. This wide distribution of finger millet has led to considerable controversy over the place of its original domestication and the identity of its wild progenitor (Hilu and de Wet 1976).

Two wild species closely resemble finger millet in gross morphology: Eleusine indica [L.] Gaertn., which is widely distributed in both Africa and Asia; and E. africana Kennedy-‘Byrne, which is predominantly African. P. J. Greenway (1945) suggested that finger millet had an African origin and that its wild progenitor is E. africana. But J. Kennedy-‘Byrne (1957) proposed that E. indica gave rise to Indian cultivars and E. africana to African cultivars.

More recent cytogenetic and morphological evidence indicates that E. africana is the closest wild relative of finger millet. Finger millet is a tetraploid with 2 n = 36 chromosomes, as is E. africana, that crosses with the cereal to produce fertile hybrids. Derivatives of such crosses are obnoxious weeds of cultivation in eastern Africa. Eleusine indica is a diploid (2 n = 18) and genetically isolated from the cereal.

In their work, K. W. Hilu and de Wet (1976) taxonomically recognized finger millet as E. coracana, subspecies coracana, and the wild and weedy African complex as E. coracana, subspecies africana. Wild finger millet is a common grass along the eastern and southern African highlands and is harvested during times of scarcity.

The antiquity of finger millet cultivation in eastern Africa is not known with certainty (Harlan, de Wet, and Stemler 1976). Impressions of wild, and possibly cultivated, finger millet spikelets occur on potsherds from Neolithic settlements at Kadero in Central Sudan that date back about 5,000 years (Klichowska 1984). Further archaeological evidence presented by Hilu, de Wet, and Harlan (1979) suggests that a highly evolved race of finger millet was grown at Axum, in Ethiopia, by the first century A.D. If these dates are correct, finger millet is the oldest known domesticated tropical African cereal.

This conclusion is not impossible. The concept of agriculture could have been introduced from West Asia into the Highlands of East Africa before the domestication of sorghum and pearl millet along the southern fringes of an expanding Sahara. The Near Eastern cultigens, wheat and barley, are adapted for cultivation on these highlands, and their introduction into eastern Africa could also have led to the domestication of native grasses as cereals.

Finger millet is variable in respect to inflorescence morphology, which is associated with selection and isolation of cultivars by farmers, rather than ecogeographical adaptation. Morphologically similar cultivars are widely grown, and African and Indian cultivars are often difficult to distinguish on the basis of morphology.

Five races of cultivated finger millet were recognized by de Wet and colleagues (1984b). Race coracana is grown across the range of finger millet cultivation in Africa and India. These cultivars resemble subspecies africana in having a well-developed central inflorescence branch. Inflorescence branches are 5 to 19 in number, essentially straight, and 6 to 11 cm long. In India, race coracana is often sown as a secondary crop in fields with pearl millet or sorghum.

The most common finger millets in both Africa and India belong to race vulgaris, which is also grown as a cereal in Indonesia. Inflorescence branches are straight, reflexed, or incurved, with all three types frequently occurring in the same field. In India, this race is often planted as a dry-season crop following the harvest of irrigated rice, and in the eastern hills it is often sown in nurseries and transplanted with the first rains of the season to assure an early harvest.

With incurved inflorescence branches, race compacta resembles vulgaris cultivars, but the inflorescences are larger and the lower inf lorescence branches are always divided in compacta. These cultivars are commonly known as cockscomb finger millets. Indian cultivars have a branch located some distance below the 4 to 14 main inflorescence branches, but African cultivars usually lack this lower branch. The race is grown in northeastern India, Ethiopia, and Uganda.

Race plana is grown in Ethiopia, Uganda, and the western and eastern ghats of India. Spikelets are large and arranged in two moderately even rows along the rachis, giving young inflorescence branches a ribbon-like appearance. Florets are often so numerous that they almost surround the rachis at maturity.

Race elongata is morphologically the most distinct of the five races of finger millet. Inf lorescence branches are long and reflexed at maturity. Cultivars grown in Malawi have inflorescence branches up to 24 cm long. More common are cultivars with inflorescence branches of 10 to 15 cm. Race elongata is grown on the East African highlands and the hills of eastern India.

At least 1 million hectares of finger millet are planted in Africa each year. It is the preferred cereal for brewing beer and is an important food crop in Uganda, Ethiopia, Malawi, Zambia, and Zimbabwe. In India, finger millet is extensively grown by tribal people on the eastern and western ghats and by commercial farmers in Andhra Pradesh and Tamil Nadu. The area under cultivation in India is close to 3 million hectares. H. Doggett (1989) indicates that land planted with finger millet in India increased by about 3 percent annually in the 1980s. Average yield per hectare also increased from 704 kilograms (kg) in the 1950s to over 1,000 kg in the 1990s as a result of breeding African germ plasm into Indian cultivars. In East Africa a breeding program is in progress to develop cytoplasmic-genetic male sterile populations, an effort which could facilitate the production of hybrid cultivars and contribute substantially to yield increases in both Africa and India.

Tef, Eragrostis tef (Zucc.) Trotter is an endemic and highly valued cereal of the Ethiopian Highlands (Costanza, de Wet, and Harlan 1979).The grain is used to make injera, an unleavened bread that is a staple in Ethiopia, and to brew beer. The wild ancestor of tef has not yet been positively identified, but Eragrostis pilosa (L.) P. Beauv., a common grass on the Ethopian highlands, is a strong possibility. T. Kotschy (1862) reported that the grains of this wild species were harvested as a food by the Sudanese while they waited for sorghum to mature. The antiquity of tef cultivation is also not known, but its popularity suggests domestication before the introduction of wheat and barley to East Africa from the Near East. W. Stiehler (1948) suggested that tef became widely distributed on the Ethiopian highlands only during the rise of the monarchy.

W. C. Harris (1844: 349) noted that 2 races of tef with brown grain and 2 with white grain were sold in Ethiopian markets. A. Trotter (1918) recognized 7 varieties of tef on the basis of spikelet and grain color.

Two species of Digitaria are endemic cultivated cereals of the Sahelo-Sudanian climatic zone of West Africa (Chevalier 1950; Porteres 1976). True fonio (Digitaria exilis [Kippist] Stapf) is grown from Senegal to Lake Chad, and black fonio (D. iburua Stapf) is grown on the Togo highlands and in Nigeria (de Wet 1977). The wild progenitors of these fonios are not known. In West Africa, Digitaria barbinodis Henrard, D. ciliaris Vanderyst, D. longiflora, and D. ternata (Hochst.) Stapf (Retz.) Persoon are aggressive wild colonizers and are harvested as cereals during times of scarcity.

Stapf (1915) pointed out morphological similarities between black fonio and D. ternata, and between fonio and D. longiflora. Fonio is a smaller grass than black fonio. It has 2 to 4 racemes per inflorescence, whereas black fonio has inflorescences with 4 to 10 racemes. Weedy races of fonio occur in Nigeria. Cultivated fonios differ from these weeds only in having lost their natural ability to disperse seeds efficiently.

R. Porteres (1976) recorded that fonio is harvested from some 721,000 acres annually, providing food to more than 3 million people during the most difficult months of the year. Fonios were already important in the fourteenth century when the traveler Ibn Batuta noted that they were extensively available in the markets between Outala in Mauritania and Bamako in Mali (Lewicki 1974: 37-8).

Little research has been done to improve the already impressive yield potential of fonios. Their adaptation to marginal agricultural land, tolerance to drought, and popularity as a food assure their survival as cereals in the arid Sahelian and Sudanian climatic zones of West Africa.

Animal fonio (Brachiaria deflexa [Schumach.] C. E. Hubb. ex Robynsis) is a weed that is commonly harvested as a wild cereal across the savanna of Africa. Farmers often encourage animal fonio to invade sorghum and maize fields, where it matures about two months before the major crop is harvested (de Wet 1977). It is sown as a cereal only on the West African Futa Jalon Highlands (Porteres 1951).

Grass weeds differ from their domesticated close relatives primarily in being spontaneous, rather than sown, and in retaining the ability of natural seed dispersal (Harlan, de Wet, and Price 1973). They do not require harvesting or sowing by humans to survive.

Avena abyssinica Hochst. is a weedy, semidomesticate of the Ethiopian highlands (Ladizinsky 1975). It is harvested, threshed, used, and sown with the wheat or barley that it accompanies as a weed. Such cultural practices lead to a loss of natural seed dispersal ability, and as the species is not consciously sown by humans, it has become an obligate weed in cultivated fields.

Indian Millets

Wheat, rice, sorghum, pearl millet, finger millet, foxtail millet, and maize are the most important cereals grown in India. Seven indigenous cereals, mostly grown on marginal agricultural land, were domesticated in India.

Raishan (Digitaria cruciata [Nees] A. Camus) and adlay (Coix lacryma-jobi L.) are native in the wet tropics of northeastern India. Raishan is grown by the Khasi people of Assam in India and by hill tribes in Vietnam. H. B. Singh and R. K. Arora (1972) reported that this cereal is grown in Assam as a secondary crop in maize or vegetable fields. It is sown in April or May and harvested in September and October. Plants tiller profusely, and culms of individual plants are tied together at time of flowering to facilitate harvesting. Mature inflorescences are rubbed by hand to collect the grains. Dehusked grains are boiled as rice or ground into flour. Raishan is also an important fodder crop in Assam, and it could become a similarly significant fodder in other tropical regions of the world.

Adlay is grown under shifting cultivation from Assam to the Philippines (Arora 1977). It was probably domesticated in tropical eastern India and introduced into Southeast Asia, but it is also possible that adlay was independently domesticated as a cereal in both India and the Philippines. The greatest diversity of cultivated adlay occurs in the Philippines (Wester 1920).

The fruit cases of wild adlay (Job’s tears) are used as beads. Fertile female spikelets of all wild Coix species are individually enclosed by an involucre that is indurated, glossy, and colored white, gray, or black. The involucres of cultivated adlay are papery, allowing for easy removal of the caryopses from the fruit cases. Adlay grains are cooked as rice or ground into flour to be used in baking bread. Adlay is often grown on banks between rice paddies.

The other five indigenous Indian cereals were probably domesticated in semiarid India where they still form an important part of dryland agriculture.

Sama (Panicum sumatrense [Roth.] ex Roem. et Schult.) is grown in India, Nepal, Sikkim, and western Myanmar (de Wet, Prasada Rao, and Brink 1984a). It is an important cereal in the eastern ghats of Andhra Pradesh and adjacent Orissa. Sama is tolerant to drought and produces a crop even in the poorest agricultural soil. It is commonly sown as a mixture with foxtail millet in sorghum or pearl millet fields, where it matures and is harvested first, followed by foxtail millet and sorghum or pearl millet. Mixed planting provides a supply of cereals starting about two months after planting to the end of the rainy season. A robust race is sometimes planted as a single crop and is an important cereal in the hills of eastern India.

Primitive cultivars of sama resemble the widely distributed Panicum psilopodium Trin., except for their persistent spikelets. This wild species crosses naturally with sama to produce fertile hybrids. Derivatives of such hybrids occur as weeds in and around cultivated fields.

Sama has been grown as a cereal in India for at least 4,500 years. S. A. Weber (1991: 107-8) pointed out that carbonized grains of sama are common at the early Harappan agricultural site of Rodji.

Sawa (Echinochloa colona [L.] Link) is grown in India, Nepal, and Sikkim (de Wet et al. 1983a). Cultivated kinds of sawa are also known taxonomically as E. utilis Ohwi et Yabuno. It is morphologically allied to Japanese millet (Echinochloa cruss-galli [L.] P. Beauv.), but sawa is tropical rather than temperate in its distribution. Furthermore, these tropical and temperate domesticated species are genetically isolated from one another (Yabuno 1966). Sawa was probably domesticated in India, whereas Japanese millet seems to have originated in northwestern China. Some Indian cultivars of sawa differ from weedy E. colona only in having spikelets that disarticulate tardily rather than readily at maturity, as is common in wild grasses. These weedy sawas frequently occur with cultivated races in the same field, and sawa could have been domesticated originally by an accidental harvest of weed sawas in fields where other cereals were planted.

Four races of sawa are recognized. Races have little geographic distinctiveness but are recognized and maintained by farmers. Race stolonifera resembles wild E. colona, except for persistence of spikelets in the cereal and disarticulation of spikelets at maturity in the weed. Race robusta has large inflorescences and is widely grown. It crosses with stolonifera. Derivatives of such hybridization gave rise to the stoloniferous race intermedia. The most distinct race is laxa. It is grown in Sikkim and is characterized by long and slender racemes.

In Africa, Echinochloa colona is also an aggressive colonizer of cultivated fields. D. M. Dixon (1969) identified grains ofE. colona among plant remains from intestines of mummies excavated at Naga ed-Dar in Egypt. The species was probably harvested as a wild cereal in ancient Egypt along the flood plain of the Nile, a practice that remains common today in times of scarcity.

Kodo (Paspalum scrobiculatum L.) is an important cereal in Kerala and Tamil Nadu and a minor cereal in India north to Rajasthan, Uttar Pradesh, Bihar, and West Bengal. The species occurs wild across the Old World tropics (Clayton and Renvoize 1982). It is an aggressive colonizer of disturbed habitats and lends itself to domestication.Wild kodo is a perennial, whereas the cultivated cereal is grown as an annual. Some cultivars of kodo millet root at lower nodes of their decumbent culms to produce new flowering culms after the first harvest. Kodo occurs in the agricultural record of India starting 3,000 years ago (Kajale 1977; Vishnu-Mittre 1977). Little racial evolution has occurred in Kodo millet.

The commonly grown kodo millet resembles spontaneous kinds in having racemes with spikelets arranged in two regular rows on one side of a flattened rachis. Two types of inflorescence aberrations occur occasionally in fields of kodo. In one variant, spikelets are arranged along the rachis in two to four irregular rows, rather than two regular rows. In the other variant, the spikelets are arranged in several irregular rows at the lower part of racemes and become two regular rows near the tip of the racemes. These aberrant plants are more robust and have fewer and better synchronized tillers than common kodo millet. Introgression with weed kodo makes it impossible for farmers to maintain these high-yielding genotypes, although they are carefully selected to provide seed for the next season (de Wet et al. 1983b). Farmers in southern India correctly believe that Kodo millet grains can be poisonous after a rain.The reason for this toxicity is ergot infection.

Korali (Setaria pumila [Poir.] Roem. et Schult.) and peda sama (Brachiaria ramosa [L.] Stapf) are domesticated Indian weeds that are widely distributed in tropical Africa and Asia. They are often harvested as wild cereals in times of scarcity and are cultivated only by the hill tribes of southern India. Wild and cultivated kinds of both korali and peda sama cross to produce aggressive colonizer populations. Farmers tend to keep the domesticated kinds pure through seed selection.

Eurasian Millets

Four millets – crab grass (Digitaria sanguinalis [L.] Scopoli), proso millet (Panicum milliaceum L.), foxtail millet (Setaria italica [L.] P. Beauv.), and Japanese millet (Echinochloa crus-galli [L.] P. Beauv.) – are widely distributed across temperate Europe and Asia.

Crab grass (D. sanguinalis) is a cosmopolitan weed. It became semidomesticated in southeastern Europe after having been harvested for millennia. Crab grass never completely lost the ability of natural seed dispersal because it was commonly harvested by swinging a basket to collect the mature grains. The species is an aggressive natural colonizer of disturbed habitats, including cultivated fields. It was a popular cereal in southern Europe during Roman times (Körnicke 1885: 279-84) and was still widely grown as mana or bluthirse in southeastern Europe during the first quarter of the nineteenth century. Crab grass was probably independently domesticated in several parts of its range. It is currently grown as a minor cereal in the Caucasus of Russia and in Kashmir.

Japanese millet (Echinochloa crus-galli) is a grass of temperate Eurasia. The barnyard grass found in the American Midwest is an introduced weed race of E. crus-galli. Echinochloa oryzoides (Ard.) Fritsch, the common weed of rice cultivation, is also distantly related to E. crus-galli. Japanese millet is grown as a cereal in China, Korea, and Japan. Cultivated kinds are sometimes, incorrectly, classified as E. frumentacea (Roxb.) Link. Little is known about the antiquity of this cereal. H. Helmqvist (1969) suggested that the species was grown in Sweden during the Bronze Age when the climate was milder than it is today. It is no longer grown as a cereal anywhere in Europe.

The genus Panicum is widely distributed throughout the warmer parts of the world and is of considerable economic importance. Several species are grown as fodder, others are harvested as wild cereals in times of scarcity, and still others are obnoxious weeds. Proso millet (Panicum miliaceum) was once widely cultivated in temperate Europe and Asia but has largely been replaced as a cereal by wheat.

The closest wild relative of proso millet, Panicum miliaceum var. ruderale Kitagawa is native to central China (Kitagawa 1937). In morphology, it resembles weed races of proso millet that occur across temperate Eurasia but is a less aggressive colonizer than the weed. These weeds represent derivatives of cultivated proso millet that regained the ability of natural seed dispersal through mutation (Scholz 1983).

Proso millet has been grown in central China for at least 5,000 years (Cheng 1973), and it is still grown on about 1.5 million hectares in China. It is also an important cereal in Mongolia, Korea, and northern India. A cultivar of proso millet with glutinous endosperm is favored in China, where its flour is used to make bread. Nonglutinous cultivars are grown in Mongolia and India, and the grains are cooked as rice.

Proso millet has been grown in southern Europe for at least 3,000 years (Neuweiler 1946). It became widely distributed as a cereal in Europe during the Bronze Age. Its popularity declined during the twentieth century, and proso millet is now grown in Europe primarily as a feed for caged birds. It is extensively variable. Five cultivated races are recognized. They are artifacts of selection by farmers and have no ecogeo-graphic validity.

Race miliaceum resembles wild var. ruderale in having numerous decumbent culms, each with several racemes. Its inflorescences are large, with spreading branches that commonly lack spikelets at the base. This is the basic race from which the other races were selected under cultivation. It is grown across the range of proso millet cultivation.

Race patentissimum resembles miliaceum in its lax panicles with spreading branches having a sterile zone at the base. Inflorescences, however, become curved at maturity because of the weight of the spikelets. Patentissimum is the common proso millet in India, Bangladesh, Pakistan, and Afghanistan. It is also grown in Turkey, Hungary, Russia, and China. Race patentissimum probably reached India from central Asia during historical times.

Races contractum, compactum, and ovatum are often difficult to distinguish from one another. They represent the highest evolved cultivars of proso millet. Inflorescences are more or less elliptic in shape. Spikelets are crowded along the panicle branches in compactum and ovatum. These branches are erect when young and become curved at maturity. Ovatum cultivars usually have smaller inflorescences than race compactum and are grown in Russia, Turkey, and Afghanistan. Compactum cultivars are grown in Japan, Russia, Iran, and Iraq. In race contractum the lower part of panicle branches are free of spikelets. Race contractum is grown in Europe, Transcaucasian Russia, and China.

Foxtail millet, Setaria italica, is grown as a cereal in southern Europe, in temperate Asia, and in tropical India. Its closest wild relative is the cosmopolitan weed, green foxtail (S. italica viridis [L.] Thell.). The latter is primarily an urban weed, but as a robust race it is also an obnoxious weed of agriculture (Pohl 1966). This giant green foxtail is derived from introgression between cultivated and wild races.

The antiquity of foxtail millet as a cereal is uncertain. The species could have been domesticated across its range of natural distribution from Europe to Japan (de Wet, Oestry-Stidd, and Cubero 1979). It has been grown as a cereal in China for at least 5,000 years (Cheng 1973) and in Europe for at least 3,000 years (Neuweiler 1946). Foxtail millet was an important cereal during the Yang-shao culture phase in China. Evidence of foxtail millet in storage jars, and the association of farming implements with the Yangshao culture, suggest that the cereal was cultivated rather than harvested from wild populations (Ho 1975). In Europe foxtail millet commonly occurs in early farming sites in Austria and Switzerland (Neuweiler 1946).

Cultivated foxtail millets are commonly divided into two cultivated complexes. The Chinese-Korean complex with large, pendulous inflorescences is recognized as race maxima, and the European complex with smaller and more erect cultivars is called race moharia (Dekaprelevich and Kasparian 1928). An Indian complex, race indica, was identified by K. E. Prasada Rao and colleagues (1987). The Indian race was derived from moharia through selection for adaptation to the tropics. It is an important cereal among hill tribes of southern India, where it is frequently grown as a mixed crop with sorghum or pearl millet.

F. Körnicke (1885: 238-44) recorded that canary grass (Phalaris canariensis L.) was grown as a cereal in southern Europe until the nineteenth century. Flour produced from its grain was mixed with wheat flour for making bread. It is still grown as a feed for birds but no longer used as a human food (Febrel and Carballido 1965). Nothing is known about the antiquity of canary grass as a cereal, and it is probably of recent domestication.