. Plant life and plant uses; an elementary textbook, a foundation for the study of agriculture, domestic science or college botany. Botany. MORE ABOUT POLLINATION 315 pollen is concealed in the throat of the corolla and the nectar is in the bottom of the spur, but both can be easily reached by the tongue of bees. Yucca and Pronuba.—-This is one of the most famous cases of mutual dependence between a plant and its polli- nating insect; there is a sort of partnership in their repro- ductive process, each being necessary to the other. The yuccas grow chiefly in deserts, especially in south- weste
. Plant life and plant uses; an elementary textbook, a foundation for the study of agriculture, domestic science or college botany. Botany. MORE ABOUT POLLINATION 315 pollen is concealed in the throat of the corolla and the nectar is in the bottom of the spur, but both can be easily reached by the tongue of bees. Yucca and Pronuba.—-This is one of the most famous cases of mutual dependence between a plant and its polli- nating insect; there is a sort of partnership in their repro- ductive process, each being necessary to the other. The yuccas grow chiefly in deserts, especially in south- western United States and Mexico; the Spanish bayonet is a commonly cultivated species. (See Figure 134.) The pronuba is a small moth most of whose life is spent upon yucca plants. Pollination is performed by the, female moth. During the day she remains hid- den within the flower. At twilight she begins her work. First she visits the stamens and collects a mass of pollen. (See Figure 135.) Still holding the pol- len, she moves about the flower and finally comes to rest astride of one of the stamens and with her head toward the stigma. (See Figure 136.) While in this position she thrusts her sharp-pointed egg-depositing organ (the ovipositor) down between the stamens, through the wall of the ovary, and in among the ovules. There she deposits an egg. As soon as this is done, she rushes to the top of the hollow pistil and vig- orously thrusts pollen down into it. She then repeats the performance, going to the top of the pistil and thrusting pollen into it after each egg is deposited. In this way the same pistil is usually pollinated several times. It is as. Fig. 135. — Pronuba collecting pollen from a stamen of yucca. The sta- mens open at the Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Coulter, John G
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectbotany, bookyear1913
