WHEAT, the most valuable, and, next to maize, the most productive of all the cereal grasses. The genus triticum, of which the species are popularly known either as wheat or wheat-grass, is distinguished by a spike with many-flowered spikelets, without stalks, and seated one on each notch of the radius, their sides directed to the radius, which is zigzag; and two giumes, of which the lower is either awned or awnless; the outer palne of each floret having at the top a notch, in the center of which is the terminal point, sometimes prolonged into an awn, or, in some species, with many florets into an awn without a notch. A. number of species are found in Britain, of which 7' repens well known as couch grass (q.v.), is the most common; but the seeds of none of tl one o • are of any value. The native country of the cultivated wheat nerally been sup posed to be the central part of Asia; but a discovery was made not many t* years ears ao by 31. Fibre of Agde, in the s. of France, that the wgilops ovata, a grass of regions near the Mediterranean, and of the w. of Asia, becomes transformed by cultivation wheat. The announcement of this discovery was at first •received with much an t P although the possibility of the transformation had been suggested by revlio11.
but it has been confirmed by subsequent observations and ex eriiXents. The genus regftops, as hitherto recognized by botanists, is distinguished from elm chiefly by its more numerous awns, the glumes of YE. ovate being genera y terminated by 3 or 4 awns, prolongations of their ribs, antiP the alere by short awns. The awns of grasses, however, afford very uncertain characters, hem.. extremely Mile to disappear through change of circumstances; and among the varieties of wheat, every farmer is familiar with some that are awned or and some that are beardless, having scarcely a trace of awn. In the wild cc ear is also much more easily broken from the rachis than in wheat. In , the very soon loses awns of its pales; and of the lateral ribs of its gluin and thus assumes the characters g of wheat, the ears at the same time losing their the grain also increasing in proportionally size, while the floral envelopes are the leaves become larger, anti the stem stronger. From seeds of thep.,.f. Buckman, in a garden in 1838, M. Fabrc obtained wheat of fair quality in 1846. , of the royal agricul tural college, repeated the experiment in first sowing was in 1855, and notwithstanding the disadvantages of cold seasons and a cold situation on the Coteswold hills, he found the spikelets eh modified in 1859, the warm summer of that year pro ducing a greater change than hail place dace in years (see Popular Science Renew for October, 1861). The identity of the principal cultivated forms of triticam
with X. orata may now be regarded as fully established. These forms have generally been included by botanists under the name T. vulgare.
Wheat has been cultivated from the earliest ages, 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 n. 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 reatuns 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 sub tropical regions, although it is a hardy plant. and when covered by snow, endures even very severe winters in the n. of Europe. For its successful cultivation, however, it requires a mean temperature of at least 55' Fain.. for 3 or 4 months of the year. It is an annual plant, and its capacity of enduring the cold of winter is of importance only in connec tion 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 u. as that of barley or oats, or even of rye. In Europe, its northern limit is about hit. 60°. The quality of the grain varies much in different soils and climates, and particular varieties arc also dis tinguished 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; and the wheat produced in Britain is not found suitable for the manufacture of macaroni, to which that of the countries near the Mediterranean is particularly adapted. Although hardy in winter and early spring, wheat becomes more delicate and susceptible of climatic influences as it advances in growth; a prevalence of dry weather, with bright sunshine from the time when it comes into ear until it is ripe, is of the greatest importance.