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Leaves. When the internodes lengthen and the spike pushes upward, the wheat is said to shoot. Previous to this, the nodes are so close together that the plant seems to consist almost entirely of leaves. There are four principal parts to the leaf: The blade; the sheath, which clasps the stem and is split down the side opposite the blade; the ligule, also clasping the culm, and located where the blade and sheath join; and the leaf auricle, thin projections growing from the base of the blade. The first leaves of the wheat plant and the germ whorl of roots do not live through the winter in some varieties.

The Flower of Wheat is constituted collectively of the organs of reproduction, together with the two inclosing chaffy

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parts. The inner of these two parts is known as a palea, while the outer and lower one is the flowering glume. The latter often bears a long appendage, characteristic of bearded wheat. These awns or beards vary greatly in length even in the same spike, and in some i varieties are deciduous upon ripening. Their color varies from light yellow to black.

Organs of reproduction in wheat; 4, ovary, o, and stig

The Spikelets.-Each consists of from ma, s, just before flowering; two to five flowers encased within two B, the same at time of flow

ering; C, flower before open- hard oval chaffy coverings called outer ing, a, anthers, f, filament,

7, fodicule; D, flower about glumes.

to open.

spikelet

In common wheat each generally matures two, and sometimes three, grains. The glumes vary greatly in form, color and size. The stem or rachis of the spike is of a zigzag form. On each of its joints or shoulders sits a single spikelet, attached by an exceedingly short rachilla. Arranged alternately on the stem, with flat sides toward the center, the spikelets usually give the head of wheat a square appearance when viewed endwise. Viewed from the side, the spike may be straight or curved; it may have uniform sides, or taper toward both ends, or only toward base or apex; or it may be clubbed at either end. The filling of the spikelets has much to do with the appearance of the spike, which varies much in different varieties. There is also great variation in compactness. Fifteen to twenty fertile spikelets, containing from 30

to 50 grains, are usually formed on a spike of wheat, the average length of which is between 3 and 4 inches. Humboldt said that in Mexico each spike of wheat averaged 90 grains, though some had as many as 160. Mummy wheat has been observed with ears containing nearly a dozen branches. There are 150 grains in one ear, and as many as 60 ears from one seed. Wheat has the advantage of extreme diminution of the number of seeds to each flower, giving richness in starch and gluten, combined with the advantage of numerous flowers on each plant, giving many seeds.

The Wheat Kernel is a dry, indehiscent, unilocular caryopsis. It is oval in shape, and has the appearance of being folded upon itself from two sides. A ventral crease marks the coming together of the two folds. At the base

of the berry opposite the crease is found the embryo, germ, or chit. At the apex is a collection of minute hairs. The entire grain fills from 20 to 30 cubic millimeters of space, of which at least thirteen-fourteenths are occupied with the starchy endosperm. The latter almost surrounds the embryo, and its cells are very irregularly shaped. The embryo is composed of the absorbent organ (scutellum), and the miniature first leaves and roots. It forms about 6 per Icent of the wheat kernel.

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Coats of a wheat kernel; The endosperm and embryo are coma, germ; b, starch cells; c, rletely enclosed by a single layer of gluten cells; d, inner coat of bran; e, coloring matter of aleurone or gluten cells. The weight of bran; fand g, outer coats of this layer is 8 per cent of that of the bran; h, epidermis of kernel. whole grain. The next covering is a single layer of collapsed cells, known as the tegmen. This is again surrounded by a third envelope, the testa, or episperm, which contains the greater part of the coloring matter of the grain. This coloring matter is of two kinds, one a palish yellow, and the other an orange yellow, and the degree in which one or the other predominates determines whether the wheat is known as white, yellow or red. The three layers just described constitute the envelope of the seed proper. They in turn are again inclosed

by the pericarp, which is also composed of three layers, all colorless. The exterior of these three membranes, the cuticle, is easily removed by rubbing. Then come two layers of cellular tissue, the epicarp (from which spring the hairs above mentioned) and the endocarp. The tegmen and testa form about 2 per cent of the weight of the grain, and the pericarp forms fully 3 per cent. Thus the bran forms at least 13 per cent of the grain.

Germination. The three conditions essential to the germination of wheat are moisture, warmth and oxygen. In the ab

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sence of any one of these the process will not begin, or if it has begun it will cease. Johnson defines the period of germination as lasting from the time when the rootlet becomes

Cross section of grain of wheat on the left. (From visible micro-photograph by Tolman.) Transverse section, on the right, of an unripe grain enlarged about 100 stores times from drawing by Bessey. 1, ovary wall or pericarp; 2, outer integument; 3, inner integument; 4, mother remains of nucellus; 5, aleurone cells; 6, starch cells.

until the

of the

seed are

exhausted and the At 41° F.,

young plant is wholly cast upon its own resources. the time required for the rootlet to appear in wheat is about six days, which time corresponds to the more general idea of the period of germination. At 51° this time is shortened about one-half. The time required for the completion of germination is 40 to 45 days at 41 to 55° and 10 to 12 days at 95 to 100°. The lowest temperature at which wheat will germinate is 41°, the highest 104°, and that of most rapid germination, 84°. This is according to Johnson. Other authorities claim that wheat will will germinate and grow on melting ice. It has also been said that it does not germinate successfully at a high temperature, and consequently should not be sown until cool weather in southern climates. Dissolved salts seem to aid germination under ordinary field conditions. In germinating, wheat absorbs from five to six times its

weight of water. It loses 1.5 per cent of its own weight in 24 hours, 6.7 per cent in 90 hours, and 11.8 per cent in 144 hours. Besides the loss in weight, marked chemical changes take place which greatly decrease its value for bread baking purposes, and probably also as a food for stock. Great loss may thus be occasioned by the sprouting of wheat in field, shock, stack or bin. Experiments indicate that sprouted wheat will regerminate and form healthy sprouts until the stem (plumule) has reached a length of 34-inch in the first germination, and an average of 80 per cent of all sprouted wheat with the length of the stem not exceeding 1/2-inch will again germinate.1

Stooling or Tillering.-Wheat, like other cereals, has the characteristic of throwing out side shoots after the plumule has appeared above the surface. These branches or culms may form at any node covered with soil. The number of such stalks from one seed varies much with conditions. There are usually at least six, but there may be from two to several dozen in extreme cases, 52 spikes having been observed. As a rule, the more favorable the conditions for plant growth, and the thinner the wheat is on the ground, the more it tillers. Cool weather during early development may result in a long period of subsequent growth which encourages tillering. also has great influence, for may not have time to stool. quite materially in different varieties. While thinner sown wheat may tiller more, a greater amount of seed per acre often increases the yield, even though there are fewer stools. Pliny is said to have declared that it was not uncommon in northern Africa and in Italy to find from 200 to 400 stalks of wheat growing from a single kernel. Humboldt put on record that in Mexico each grain of wheat produced 40 to 70 stalks. It is probable that each of these men was seeing with the eyes of an enthusiast.

Time of seeding

late sown wheat
The habit varies

The culms are from a single seed originally at a.

A stool of wheat.

The Growth of a Wheat Plant is the aggregate result of the enlargement and multiplication of the cells which comprise it. 1 Rept. N. D. Sta., 1901, p. 107.

control of heat is exercised by sowing

By selecting soils, fertilizing and chang unavailable to available forms, food ca regulated, and water, acting as a solv very largely regulated as to amount by That the growth and multiplication of tion of material within the plant has lo wheat, as in many other plants, there i development of roots soon after the fir some low-lying leaves are put forth whi roots is being formed. In a wheat plan roots had penetrated the soil over 1 fo system of roots has been formed, the st almost to mature stature. Perhaps the developed by the time that the formati

The leaves of the wheat plant, with have been considered as little laborato table matter. Under the influence of extract carbonic acid from the atmosph of the raw materials of these little facto it, eliminate the oxygen, and from the res sugar, cellulose, straw-gum, vasculose, an ters composed of carbon, oxygen and hyd tem of canals penetrates every part canals are filled with water, which ent leaves do not absorb water to any appr in constant motion until it is exhaled fro one hour of insolation a leaf of wheat water equal to its own weight. Upor moving water are borne raw materials d cell factories, such as nitrates, phospho

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