The wheat plant. Structure. Growth and reproduction

Young wheat plants have a bright green color and look like grass. The mature plants grow 2 to 5 feet (0.6 to 1.5 meters) tall. They turn golden-brown when ripe.

Structure. The main parts of a mature wheat plant are the roots, stem, leaves, and head. Wheat has two types of roots, primary and secondary. Three to five primary roots grow out of the seed, about 1 ½ to 3 inches (3.8 to 7.6 centimeters) below the surface of the soil. These roots usually live for only six to eight weeks. As the stem begins to grow out of the soil, the secondary roots form just below the surface. They are thicker and stronger than the primary roots and anchor the plant securely in the soil. Most of the root system lies in the upper 15 to 20 inches (38 to 50 centimeters) of soil. But if the soil is loose, the root system may extend as deep as 7 feet (21 centimeters).

Most wheat plants have a main stem and several additional stalks, called tillers. Each leaf of a wheat plant has a sheath and a blade. The sheath wraps around the stem or tiller. The blade, which is long, flat, and narrow, extends from the top of the sheath. Each blade is on the opposite side of the stem from the blade that is just below it.

The wheat plant grows up to 5 feet (1.5 meters) high and turns golden-brown when ripe. The head of the plant holds from 30 to 50 kernels of grain. Many kinds of wheat have bristly hairs, called beards or awns, which extend from the head

A wheat head, also called a spike, forms at the top of each main stem and tiller. The head is composed of a many-jointed stem. The head carries clusters of flowers, called spikelets, which branch off from each joint. Each primary spikelet contains a wheat kernel wrapped in a husk. Many kinds of wheat have bristly hairs, called awns or beards, which extend from the spikelets. Atypical wheat spike bears 30 to 50 kernels.

A wheat kernel is usually 1/8 to 3/8 finch (3 to 9 millimeters) long. It has three main parts—the bran, the endosperm, and the germ. The bran, or seed coat, covers the surface of the kernel. The bran has several layers and makes up about 14 per cent of the kernel. Inside the bran are the endosperm and the germ. The endosperm forms the largest part of the kernel—about 83 per cent. The germ makes up only about 3 per cent of the kernel. It is the part of the seed that grows into a new plant after sowing.

Cross section of kernel of wheat

Growth and reproduction. A wheat kernel begins to absorb moisture and swell shortly after planting. The primary roots appear, and the stem starts growing toward the surface of the soil. One to two weeks later, the young plant appears above the ground. In less than a month, leaves appear and the tillers and secondary roots begin to grow.

in spring when conditions are favorable, stems elongate (lengthen) from the leaf sheaths. Heads appear on the tillers soon afterward. A few days after the spike emerges from the sheath, the flowers are pollinated and develop into wheat kernels. Usually, each wheat flower pollinates itself. Occasionally, however, pollen from one flower is carried by the wind and fertilizes another flower.

Wheat becomes fully ripe about 30 to 60 days after flowering, depending on the weather. During the ripening period, the kernels increase in size and gradually harden. The entire plant becomes dry and turns golden-brown. Ripe kernels may be white, red, yellow, or even purple, depending on the variety of wheat.