. Bulletin. 1901-13. Agriculture; Agriculture. Fig. 1.—Flowers of siftriui • ippi trance while pollen is being shed; (6 Stigma and anthers avoiding each other, (c) Receptive stigma and deciduous anthers. (From drawings by E. E. Lower.) do so when their pistils have reached a receptive condition. The pis- tils of such flowers are perfectly protected from pollen from all sources until they are receptive. PI. IV, tig. <i. shows a fully open, recep- tive begonia flower, while tig. 7 shows the two calyx lobes securely closed over the young pistil of a similar but younger flower. Proter- a
. Bulletin. 1901-13. Agriculture; Agriculture. Fig. 1.—Flowers of siftriui • ippi trance while pollen is being shed; (6 Stigma and anthers avoiding each other, (c) Receptive stigma and deciduous anthers. (From drawings by E. E. Lower.) do so when their pistils have reached a receptive condition. The pis- tils of such flowers are perfectly protected from pollen from all sources until they are receptive. PI. IV, tig. <i. shows a fully open, recep- tive begonia flower, while tig. 7 shows the two calyx lobes securely closed over the young pistil of a similar but younger flower. Proter- androus flowers open while the pistils are immature, but even here modifications are met with which insure the pistils against premature pollination. The stigmatic surfaces are often folded together, thus preventing pollination even though the immature pistil be exposed. Fig. 1 shows the interesting behavior of flowers of Sabbatia angularis; a shows the condition of the flower when the anthers discharge their pollen, two petals and one stamen having been cut away in order to show the young pistil, which at this stage lias no stigmatic surface exposed. Instead of growing straight out and thus coming in contact with the drying anthers, the pistil invariably grows out to one side, passing between the filaments of the stamens. The stamens at this stage begin to bend to the side of the flower opposite the one occupied. 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 United States. Bureau of Plant Industry, Soils, and Agricultural Engineering. Washington Govt. Print. Off
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