. Morphology of gymnosperms. Gymnosperms; Plant morphology. 200 MORPHOLOGY OF GYMNOSPERMS but two weeks later they are mm. long, the nucellus being homogeneous and not wholly inclosed by the integument (fig. 228).' Not all the buds of the dwarf shoots are fertile, and the strobili in those that are range in number from one to six. In such a bud the sequence of structures from outside inward is as follows: brown bud scales, green scale leaves, foliage leaves, strobili, foliage leaves. About. Figs. 228-230.—Ginkgo biloba: early stages in the development of the ovule; fig. 228, nuceUus in Ap
. Morphology of gymnosperms. Gymnosperms; Plant morphology. 200 MORPHOLOGY OF GYMNOSPERMS but two weeks later they are mm. long, the nucellus being homogeneous and not wholly inclosed by the integument (fig. 228).' Not all the buds of the dwarf shoots are fertile, and the strobili in those that are range in number from one to six. In such a bud the sequence of structures from outside inward is as follows: brown bud scales, green scale leaves, foliage leaves, strobili, foliage leaves. About. Figs. 228-230.—Ginkgo biloba: early stages in the development of the ovule; fig. 228, nuceUus in April, not yet covered by integument; no archesporium can be distinguished at this stage; Xi$; fig. 229, condition May i; X12; fig. 230, May i, megaspore mother cell surrounded by "spongy tissue"; X 325.— After Miss Carothers (46). the first of May the ovules are mm. long; the prominent nucellar beak has developed, in some cases protruding from the micropyle; a large pollen chamber has been formed, which often contains pollen grains developing tubes; and the sporogenous tissue is in all stages from immature mother cells to complete tetrads. According to HiRASE (22), the pollen chamber results from the exclusive growth of the external tissue of the beak, the inner tissue thus becoming rup- tured and disorganized. Usually one mother cell functions, two functioning mother cells. 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 Merle, 1851-1928; Chamberlain, Charles Joseph, b. 1863; Coulter, John Merle, 1851-1928. Morphology of spermatophytes. Part I. Gymnosperms. Chicago, University of Chicago Press
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