. Principles of modern biology. Biology. Reproduction in Multicellular Plants - 225. Fig. 12-25. Germinating grains. A, corn grain in early stage of germination. The primary root has penetrated the sheath and is emerging from the grain. B, a later stage in the germination of a corn grain. The primary root has numerous root hairs, and the plump epicotyl has emerged. C, a germinating wheat grain, showing the primary root with hairs, the short blunt epicotyl, and several young side roots. (From Co//ege Botany, by Fuller and Tippo. Holt, Rinehart and Winston, Inc.) attracing function of the smalle
. Principles of modern biology. Biology. Reproduction in Multicellular Plants - 225. Fig. 12-25. Germinating grains. A, corn grain in early stage of germination. The primary root has penetrated the sheath and is emerging from the grain. B, a later stage in the germination of a corn grain. The primary root has numerous root hairs, and the plump epicotyl has emerged. C, a germinating wheat grain, showing the primary root with hairs, the short blunt epicotyl, and several young side roots. (From Co//ege Botany, by Fuller and Tippo. Holt, Rinehart and Winston, Inc.) attracing function of the smaller true petals (for example, in poinsettia and dogwood, Fig. 12-27). In wind-pollinated flowers (for example, the Cottonwood, Fig. 12-28), petals and sepals are either lacking or inconspicuous, and usu- ally the pistils and stamens occur in separate flowers. Such incomplete flowers are held aloft on the outermost branches of the plant, where there is a maximum exposure to the wind; and usually wind-pollinated flowers ap- pear early in the spring, before the leaves come out to interfere with the transfer of the pollen, which is produced in very large amounts. Most of our common deciduous trees (maples, elms, willows, oaks, etc.) pos- sess wind-pollinated flowers. Frequently a multiple cluster of flowers is borne on one stalk (peduncle), which may or may not be branched (Figs. 12-27 and 12-28). Such floral clusters technically are called inflorescences, of which there is a wide va- riety of types. One very common type of inflorescence is possessed by the dandelions, daisies, sunflowers, dahlias, and the other members of a large family, the Compositae. The large "sunflower," for example, is an inflorescence composed of a multitude of very small individual flowers, which are of two sorts (Fig. 12-29). The sterile ray flowers, which lack both pistils and stamens, are ar- ranged radially around the outer margin of the circular head. These ray flowers account for most of the
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