. Morphology of gymnosperms. Gymnosperms; Plant morphology. EVOLUTIONARY TENDENCIES AMONG GYMNOSPERMS 429 Cycadales, the primary root is polyarch. Even Araucaria, which is exceptional in many respects, has been reported with six root poles, although two is the usual number. In the Coniferales the reduction in number of root poles is closely related to the reduction in number. Fig. 462.—Diagrams illustrating the cotyledonary node of gymnosperms and its vascular connections with the cotyledons: the lobes indicate cotyledons.—Prepared by Sister Helen Angela. Series A, Cycadales: I, Dioon spinulos
. Morphology of gymnosperms. Gymnosperms; Plant morphology. EVOLUTIONARY TENDENCIES AMONG GYMNOSPERMS 429 Cycadales, the primary root is polyarch. Even Araucaria, which is exceptional in many respects, has been reported with six root poles, although two is the usual number. In the Coniferales the reduction in number of root poles is closely related to the reduction in number. Fig. 462.—Diagrams illustrating the cotyledonary node of gymnosperms and its vascular connections with the cotyledons: the lobes indicate cotyledons.—Prepared by Sister Helen Angela. Series A, Cycadales: I, Dioon spinulosum (occasional); 2, D. edule (occasional); 3, D. spinulosum, Ceratozamia, Microcycas; 4, D. edule; 5, Zamia floridana, Cycas spp.; 6, Cycas siamensis; 7,C. Seemannii. Series B, Coniferales: 1-6, various species of the Pinaceae; 7, Libocedrus, Taxus, Cephalotaxus. Series C, Ginkgoales, Gnetales, and exceptional Coniferales: /, 2, Ginkgo biloba/ J, 4, Araucaria spp.; 5, Podocarpus; 6, 7, Gnetales. of cotyledons, for when the dicotyledonous condition is reached, the root is diarch. Among the Cycadales, on the other hand, although some have reached the diarch state, the characteristic root is tetrarch, the intercotyledonary poles persisting after the dicotyledonous con- dition is attained. An important consideration here, however, is the fact that there is often a reduction in the number of poles in. 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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