. Morphology of gymnosperms. Gymnosperms; Plant morphology. 126 MORPHOLOGY OF GYMNOSPERMS of Zamia, which are less than 3 mm. in length. The color is as various as the size, white, creamy, pink, and various shades of red predominating. Within the same species there is not nearly so much variation in color of ovules as in size. Some ovules are densely hairy, as those of Cycas revoluta; while others, as those of Dioon, are perfectly smooth. The general topography of the ovule, which is fairly well known in all the genera, is shown in fig. 117. Important among the earlier contributions are those
. Morphology of gymnosperms. Gymnosperms; Plant morphology. 126 MORPHOLOGY OF GYMNOSPERMS of Zamia, which are less than 3 mm. in length. The color is as various as the size, white, creamy, pink, and various shades of red predominating. Within the same species there is not nearly so much variation in color of ovules as in size. Some ovules are densely hairy, as those of Cycas revoluta; while others, as those of Dioon, are perfectly smooth. The general topography of the ovule, which is fairly well known in all the genera, is shown in fig. 117. Important among the earlier contributions are those of Warming (8, 9) on Cycas in 1877 and 1879, and of Treub (ii, 13) on Ceratozamia and Zamia in 1881 and 1884. Later, Wors- DELL (270) paid particular atten- tion to the anatomy of the sporo- phylls of most of the genera. Lang (22) studied several stages in the development of the ovule of Stangeria, and Oliver (36) made a comparative study of the ovules of the older gymnosperms. In 1904 Matte (40) and Miss St OPES (42) published inde- pendently and almost simul- taneously very comprehensive accounts of the vascular anatomy of the sporophylls and ovules of all the genera. Matte's account treats of the entire vas- cular structure of the Cycadales, while Miss Stopes deals particu- larly with the ovules, and includes a discussion of the integument as well as of the vascular system. In 1906 Chamberlain (46) described the ovule of Dioon edule, paying particular attention to the structure of the integument and Fig. 117.—Dioon edule: longitudinal section of ovule after pollination, but about three months before fertilization: a, abscission layer; e, endosperm; i, inner fleshy layer (between i and »); ib, bundle of inner vascular system; m, micro- pyle; n, free portion of nucellus; o, outer fleshy layer of integument; oh, bundle of outer fleshy layer; p, basal papilla; s, stony layer of integument; X2.—After Chambeklain (46).. Please note that these images are extracted f
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