. Botany, an elementary text for schools. Botany. 130 FERTILIZATION AND POLLINATION 204. Anther of u z a 1 e a , openin g l>y termi- nal pores. 265. Most flotvers are so constructed as to increase the chances of cross-pollination. We have seen (261) that the stigma may have the power of selecting foreign pol- len. The commonest means of insuring cross- pollination is the different times of maturing of stamens and pistils in the same flotver. In most cases the stamens mature first: the flower is then proterandrous. When the pistils mature first the flower is proterogynous. {Aner, andr, is a
. Botany, an elementary text for schools. Botany. 130 FERTILIZATION AND POLLINATION 204. Anther of u z a 1 e a , openin g l>y termi- nal pores. 265. Most flotvers are so constructed as to increase the chances of cross-pollination. We have seen (261) that the stigma may have the power of selecting foreign pol- len. The commonest means of insuring cross- pollination is the different times of maturing of stamens and pistils in the same flotver. In most cases the stamens mature first: the flower is then proterandrous. When the pistils mature first the flower is proterogynous. {Aner, andr, is a Greek root often used, in combinations, for stamen, and gyne for pistil.) The dif- ference in time of ripening ma}^ be an hour or two, or it may be a day. The ripening of the stamens and pistils at different times is known as dichogamy, and flowers of such character are said to be dichogamous. There is little chance for dicho- gamous flowers to pollinate themselves. Many flowers are imperfectly dichogamous—some of the anthers mature simul- taneously with the pistils, so that there is chance for self- pollination in case foreign pollen does not arrive. Even when the stigma re- ceives pollen from its own flower, cross-fertilization may result (261). ^"^'^^ The hollyhock is 206. Flower of hollyhock; proterandrous. Dr O t C ran dr O U S Fig. 206 shows a flower recently expanded. The center is occupied by the column of stamens. In Fig. 207, showing an older flower, the long styles are 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 Bailey, L. H. (Liberty Hyde), 1858-1954. New York Macmillan
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