. Morphology of gymnosperms. Gymnosperms; Plant morphology. 282 283 Figs. 282, 283.—Sequoia sempervirens: fig. 282, longitudinal section of oviile, showing six megaspore mother cells; pollen tubes are growing down between nucellus and integument; March 12, 1902; X83; fig. 283, longitudinal section of nucellus, showing eight germinating megaspores, each containing two nuclei; April 25, 1902; X116.—^After Lawson (92). being clustered about the upper third or fourth of the remarkably elongated functional megaspore (42). In Cryptomeria japonica (93) there are four tetrads formed, and the centrally
. Morphology of gymnosperms. Gymnosperms; Plant morphology. 282 283 Figs. 282, 283.—Sequoia sempervirens: fig. 282, longitudinal section of oviile, showing six megaspore mother cells; pollen tubes are growing down between nucellus and integument; March 12, 1902; X83; fig. 283, longitudinal section of nucellus, showing eight germinating megaspores, each containing two nuclei; April 25, 1902; X116.—^After Lawson (92). being clustered about the upper third or fourth of the remarkably elongated functional megaspore (42). In Cryptomeria japonica (93) there are four tetrads formed, and the centrally placed megaspore of the group of twelve to sixteen functions. In Libocedrus decurrens (131) one to three tetrads appear, from which a single functioning megaspore is selected; and in Pinus silvestris (363, 166) and Callitris two embryo sacs have been observed. It may be inferred that two or more mother cells and tetrads may occur in any of the Pinaceae, but thus far they seem to be especially characteristic of the Taxodineae and the 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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