Wheat, the most valuable of all the cereal grasses. The genus Triticum, of which the species are popularly known either as Wheat or Wheatgrass, is distinguished by a spike with many-flowered spikelets, without stalks, and seated one on each notch of the rachis, their sides directed to the rachis, which is zigzag; and two glumes, of which the lower is either awned or awnless; the outer palea of each floret having at the top a notch, in the centre of which is the terminal point, sometimes prolonged into an awn, or, in some species, with many florets tapering into an awn without a notch. (See the diagrams of a wheat spikelet and a wheat grain at GRASSES.) A number of species are found in Britain, of which T. repens, well known as Couch Grass (q.v.), is the most common; but the seeds of none of them are of any value. The native country of the cultivated wheat has generally been supposed to be the central part of Asia; it has been reported to have been seen growing wild in Mesopotamia, Kurdistan, and elsewhere, but the fact has not been proved. M. Fabre asserted, after a series of experiments in 1838-46, that the Ægilops ovata, a grass of the regions near the Mediterranean and of the west of Asia, had under his superintendence been transformed into wheat; but it is suspected that his grasses were hybridised by wheat. It is commonly believed, however, that the cultivated varieties of wheat are derived from some of the species of the genus Ægilops.
Wheat has been cultivated from the earliest ages, seems to have been cultivated in China 3000 years B.C., is found in prehistoric European lake-dwellings, and was a chief crop in ancient Egypt and Palestine, as it still is in all the temperate parts of Europe, Asia, and Africa. It is cultivated to a considerable extent in the north of India. In North America it is very extensively cultivated, and many parts of the United States and British provinces are admirably adapted to it. Wide regions of South America are equally suitable, and wheat of the finest quality is produced in Australia. In the torrid zone wheat does not succeed, except in elevated situations; but it nowhere succeeds better than in subtropical regions, although it is a hardy plant, and when covered by snow endures even very severe winters in the north of Europe. For its successful cultivation, however, it requires a mean temperature of at least 55° F. for three or four months of the year. It is an annual plant, and its capacity of enduring the cold of winter is of importance only in connection with the advantage to be derived from sowing in autumn, so as to have it more forward in spring. Its cultivation does not extend so far north as that of barley or oats, or even of rye. In Europe its northern limit is about 60° lat. The quality of the grain varies much in different soils and climates, and particular varieties are also distinguished by difference of quality as well as by external characters. The wheat of the eastern parts of Britain, where the climate is comparatively dry, is superior to that of the western parts, where the sky is more cloudy and the climate more humid, although the crops in the west are not less luxuriant.
Common Wheat (T. vulgare, or sativum) grows to a height generally of 3 or 4 feet, and has ears or spikes generally 3 or 4 inches long; the spike 4-cornered, the spikelets about 4-flowered; the paleæ ventricose, ovate, truncate, mucronate or awned, compressed under the point, rounded at the back, the grain free. In consequence of long cultivation, in a great variety of climates, the cultivated varieties of wheat are very numerous. New varieties are continually coming into notice; and many are in high estimation in particular districts, although little known beyond them. Some botanists have attempted to distinguish species among them, appropriating the name T. æstivum to the awnless kinds, and T. hybernum to the awned; but intermediate forms are very numerous, and the length or shortness of the awn seems to depend upon accidental circumstances. Nor do the awnless or beardless kinds perfectly correspond with the Summer Wheat of farmers, preferred for sowing in spring with a view to a crop in the same season, and the awned or bearded kinds to the Winter Wheat, sown in autumn; as some of the hardy varieties of Winter Wheat are awnless, and some of those usually sown in spring are bearded. Besides being classified as Bearded and Beardless, the varieties in cultivation are also distinguished, according to the colour of the grain, as White and Red wheats. Some having the ears covered with a short soft down are known as Woolly wheats. There are also differences in the length and compactness of the spike, and in the size and form of the grain, which is more rounded in some, and more elongated in others. A number of varieties having the spike very compact or square have been sometimes classed together under the name of T. compactum, and the distinction is very obvious and permanent, although there is no reason for regarding it as characterising a distinct species. Akin to this is the Mummy Wheat (T. compositum), in which the spike is branched, and which used to be described on totally insufficient evidence as having been produced from seeds found in mummy-cases in Egypt. Mummy wheat has been grown in England of which the ears have had 10 or 11 branches, and 150 grains have been found in one ear; whilst 60 ears have been produced by a single seed. Notwithstanding these apparent advantages, however, this variety does not serve the purposes of the farmer so well as some others. In another group of varieties with compact ears (T. turqidum of some botanists) the glumes are remarkably tumid, and always awned. Polish Wheat (T. polonicum) is a well-marked, coarse type. Spelt (T. spelta) is probably only a race of T. sativum; it was cultivated by the Swiss lake-dwellers and the ancient Romans, and is still grown in the mountainous parts of Europe and elsewhere.
The red varieties of wheat are generally more hardy than the white; the grain is inferior in quality, and yields less flour, but these disadvantages are more than counterbalanced in many soils and situations by the greater productiveness of the crop. Red wheats are therefore preferred for comparatively poor soils, but the white kinds are generally cultivated wherever the soil and climate are suitable. The varieties with long straw yield the best crops in dry seasons, but the short-strawed kinds are best when the season is wet. Wheat is particularly suited to clay soils and rich heavy loams; but with good farming excellent crops are produced even on light sandy or gravelly and on chalky soils. Where the climate is moist a light dry soil is most suitable; soft deep soils being productive chiefly of straw. The land intended for wheat must, at least in Britain, be in a high state of cultivation and fertility. Wheat is commonly sown after green crops, beans, or bare fallow, and often after grass or clover. It may be sown, at least in autumn or the beginning of winter, when the ground is so saturated with moisture that any other kind of grain would be almost sure to perish. It is either sown broadcast or in drills, and the practice of drilling becomes more and more prevalent, on account both of the saving of seed and of the superiority of the crops produced. The land prepared for wheat is very often manured with farmyard manure or artificial manures.
The relative proportions of straw and grain differ very much in different varieties of wheat, and according to differences of soil, climate, and season. The proportion of the weight of grain to that of the whole plant when dried so as to be ready for stacking varies from 20 to 47 per cent. The composition of the grain itself varies considerably as to the proportions of starch, gluten, &c. which it contains. American wheats are drier than European wheats in the proportion of 10.27 to 14 per cent. of moisture; the carbo-hydrates (starch, &c.) average 72 per cent. instead of 68 per cent., as in English wheat. American wheat has a small grain, very free from fibre (bran), very rich in carbo-hydrates and oil, but deficient in albuminoids—not necessarily the best indication of value. European wheat has usually 13 per cent. of albuminoids (gluten, &c.), and sometimes 19.5 per cent. American wheats have an average of 11.95 per cent., and those from the Pacific coast only 8.6 per cent. Australian and Egyptian wheats, both remarkably fine, are also somewhat deficient in albuminoids. 100 parts of the grain of European wheat, dried in the ordinary manner, have yielded water, 14.83; gluten, 19.64; albumen, 0.95; starch, 45.99; gum, 1.52; sugar, 1.50; oil, 0.87; vegetable fibre, 12.34; ash, 2.36—total, 100.00. Wheat ash is rich in phosphoric acid, magnesia, and potash.
The value of wheat depends mainly on the quantity of fine flour which it yields; the best wheat yielding 76–80 per cent., sometimes even 86 per cent. of fine flour, whereas inferior kinds seldom yield more than 68 per cent., and sometimes only 54–56 per cent. In general the smoother and thinner the grain is in skin the greater is the produce of fine flour. The greater part of the husk of wheat is separated from the flour by the miller, and is known as bran. That portion of the bran which is more finely divided than the rest receives the name of sharps or pollard. See the articles BRAN, FOOD, BREAD.
Wheat being the most esteemed of all the cereals, particularly for the making of bread, the increase of its cultivation and use has marked the progress of agriculture and of wealth in many countries. It is only in comparatively recent times that bread made of wheat has become a common article of food among the labouring classes in Britain. In the 8th century the monks of the abbey of Bury St Edmunds ate barley-bread, because the income of the abbey would not admit of their using wheaten bread regularly. At a later period wheat was largely used, at least in the southern parts of England, for a short time after harvest, but the supply was soon exhausted, and recourse was again had to inferior kinds of food. From Walter of Henley's Husbandry (ed. by Eliz. Lamond, 1892) we learn that in the early 13th century wheat was expected to produce only five- fold (as compared with say fourteen-fold now). Down to the end of the 17th century wheaten bread was a principal article of food only among the more wealthy; and the servants in their houses were still furnished with oats, barley, and rye. In the northern parts of England, as well as in Scotland, the use of wheaten bread was comparatively rare even at the middle of the 18th century. 'So small was the quantity of wheat used in the county of Cumberland,' says Eden, in his History of the Poor (1797), 'that it was only a rich family that used a peck of wheat in the course of the year, and that was at Christmas. The usual treat for a stranger was a thick oat-cake (called haver-bannock) and butter. An old labourer of eighty-five remarks that when he was a boy he was at Carlisle market with his father, and wishing to indulge himself with a penny loaf made of wheat-flour, he searched for it for some time, but could not procure a piece of wheaten bread at any shop in the town.' At the period of the Revolution, 1689, the quantity of wheat grown in England was estimated at about 14,000,000 bushels, or about three bushels to each of the population, which was then under five millions. In 1828 about 100,000,000 bushels were produced, or about seven bushels to each of the population, then under fifteen millions. Between 1799 and 1800 the price of wheat in England rose from 69s. per quarter to 113s.; in 1801 it was 119s.; and next year sank to 69s., rising again to 106s. in 1810, and 126s. in 1812. Since 1817 (when it was 86s.) it has greatly fallen; the average price for the first time touching as low a point as 30s. in 1886, and 28s. in 1892. For the varying price and the controversies therewith connected, see CORN LAWS.
In 1891 there were 2,192,393 acres under wheat in England, 61,590 acres in Wales, 53,294 acres in Scotland, and 80,870 acres in Ireland. The estimated produce of this, in bushels of 60 lb. each, was as follows: England, 68,694,456 bushels; Wales, 1,461,740 bushels; Scotland, 1,971,067 bushels; and Ireland, 2,615,437 bushels—giving a total of 74,742,700 bushels, of 60 lb. each, for the United Kingdom. To supplement the home production of wheat no less than 123,784,192 bushels of wheat, besides flour equal to other 41,830,008 bushels, were imported into the United Kingdom in 1891. The total imports of wheat for 1891 were thus equal to 165,614,200 bushels, giving a wheat supply for that year of 240,356,900 bushels, or a little over 6 bushels per head of the population. It will be observed that the quantity of wheat now imported into the United Kingdom is more than double that produced at home. Year by year the imports increase and the home production declines. Meanwhile the price fell from an average of 58s. 8d. per quarter in 1873 to 22s. 10d. per quarter in 1894; in 1897 it rose to 30s. 2d., and in 1898 rose suddenly to 36s., and even during the Cuban war to 56s. As the result of the fall in price the area under wheat in the United Kingdom decreased by more than half between 1874 and 1895; but from 1,417,641 acres in 1895 it increased again to 2,102,220 acres in 1898. In 1895 the wheat imported comprised 67,615,785 cwt. from foreign countries and 14,134,170 from Greater Britain. In 1897 there came from Greater Britain 5,393,360 cwt., and from foreign countries 57,346,820 cwt.; besides 18,680,669 cwt. of wheaten flour. In 1898 the quantities were 50,466,780 cwt. of wheat from foreign countries and 14,761,550 cwt. from our own possessions, besides 21,071,109 cwt. of wheaten flour. Almost all the flour comes from the United States on the one hand and Canada on the other. The unground wheat comes mainly from the United States and Russia, India and Canada being the next most important sources of supply. The United States and
Russia seem likely to maintain the lead. There has lately been much discussion as to the probable future of wheat cultivation in the United Kingdom. With prices averaging 30s. to 35s. per quarter—nearly 20s. per quarter less than prior to 1879—wheat cannot now be grown at a profit in many parts where it was formerly cultivated with success. Indeed, wheat cultivation is being persevered with only in soils and situations specially favourable to it. Through the superior systems of farming pursued the produce of wheat per acre in the United Kingdom is greater than in any other country, but the cost of production is necessarily much higher than on the rich virgin soils of comparatively new countries.
The Spaniards introduced wheat-culture into Mexico about 1530; wheat was first planted in New England in 1602, and in Virginia in 1611. The growth of the acreage in the United States has been phenomenal, especially since the development of the central states in the upper Mississippi valley, and again on the Pacific coast. In California the crop in 1850 was but 17,200 bushels, whereas in 1898 it was 12,224,403 bushels. In the same year Minnesota produced 78,417,912 bushels; Ohio, 42,103,173; Kansas, 64,939,412; Indiana, 38,426,029; North Dakota, 55,654,445; South Dakota, 42,040,923; followed by Illinois, Iowa, Oregon, Nebraska, Pennsylvania, Missouri, and Michigan. The total wheat crop of the United States was 260,146,900 bushels in 1869-70, since which it has increased (with fluctuations) to 530,149,168 in 1897-98. The total exports of wheat and wheat flour were 319,186,871 in 1897-98, 313,021,235 being retained for domestic consumption. The acreage of the United States in 1898 may be put at about 44,000,000; Russia, 29,000,000; France, 17,200,000; United Kingdom, 2,155,000; Australasia, 5,000,000; and the Argentine Republic in 1899, 7,904,000 acres, yielding about 94,750,000 bushels, and the export in 1898 being about 24,450,000 bushels.
The principal diseases to which wheat is subject, some of which are productive of great loss to the farmer, are either owing to or connected with the presence of parasitic fungi. The chief of these diseases, noticed separately, are Bunt, Mildew, Rust, and Smut. Wheat is also liable to injury from several insect pests, such as Wireworms, and various other Corn Insects (q.v.). The Hessian Fly is separately discussed. Ear-cockles (also called 'purples' or 'peppercorn') is a disease in wheat associated with the abundant presence of a Threadworm (q.v.) parasite. This minute animal has received various names—e.g. Vibrio tritici, Anguillula tritici, but is now usually called Tylenchus scandens. An infested or mildewed ear of wheat contains some ten larvæ in each grain; these lie quiescent, and can so remain for many years, surviving what appears to be very thorough desiccation. If the grain be sown the larvæ become active, and migrate into the soil. Thence they return to the young wheat-plants, into which they insinuate themselves, and may there spend the winter. With the growth of the plant the threadworms ascend the stem and finally pass into the ears. There they become sexually mature, and the females deposit eggs. After that the parent forms apparently die, but the eggs develop into larvæ.
See AGRICULTURE, and books there cited; CEREALIA; CULTIVATED PLANTS; GRASSES; STRAW; PLANTS (DISEASES OF); Vilmorin, Les Blés Meilleurs (1881); and on Ear-cockles, Davaine, Recherches sur l'Anguillule du Blé (1857), and the researches of Ritzema-Bos in the Biologisches Centralblatt (1888).