. Lessons in botany. Botany. 204. BOTANY. organs. Now the fern leaf bears the spores and the spore forms the prothallium. So it is in the flowering plants. The stairen bears the small spores—pollen grains—and the pollen grain. Fig- 182. Diagrammatic section of a flower. Ke, calyx; K, corolla ; A the filament, and <z, the anther, of the stamen ; p, pollen-cells, some in the anther, others on the stigma ; F, the ovary, surmounted by the style, g, and the stigma, n (this ovary contains one ovule, which has a single coat, i, enclosing the ovule-body, S) ; em, the embryo-sac; E, germ-cell; /j, a
. Lessons in botany. Botany. 204. BOTANY. organs. Now the fern leaf bears the spores and the spore forms the prothallium. So it is in the flowering plants. The stairen bears the small spores—pollen grains—and the pollen grain. Fig- 182. Diagrammatic section of a flower. Ke, calyx; K, corolla ; A the filament, and <z, the anther, of the stamen ; p, pollen-cells, some in the anther, others on the stigma ; F, the ovary, surmounted by the style, g, and the stigma, n (this ovary contains one ovule, which has a single coat, i, enclosing the ovule-body, S) ; em, the embryo-sac; E, germ-cell; /j, a pollen-tube penetrating the style, and reaching the germ-cell through the micropyle of the ovule. forms the prothallium. The prothallium in turn forms the sex- ual organs. The process is in general the same as it is in the ferns, but with this special difference: the prothallium and the sexual organ of the flowering plants are very much reduced. 335. The male prothallium is reduced to the pollen grain. —In fact the pollen grain is male prothallium and sexual organ all in one, so reduced has it become. A young pollen grain of trillium is shown in fig. 183. It has two cells. The entire pollen grain , may be considered the antheridium, the larger cell Nearly mature representing the wall while the smaller cell is the pollen grain of tril- . Hum. The smaller generative cell. ihe latter corresponds to the cell is the genera- . tive cell. central cell of the fern antheridium. In the angiosperms it divides to form two sperm cells. These cor-. 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 Atkinson, George Francis, 1854-1918. New York, H. Holt and company
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