. Morphology of gymnosperms. Gymnosperms; Plant morphology. GINKGOALES 187 VASCULAR ANATOMY The transverse section of the stem of Ginkgo shows the general features of Coniferales, namely, a comparatively narrow cortical zone, a thick and compact cylinder of secondary wood developed by a persistent primary cambium (in contrast with Cycadales), and a relatively small pith (in contrast with Cordaitales). In the dwarf shoots, however, the pith is large and the zone of wood comparatively narrow. The primary xylem is endarch, and there is no distinct. Fig. 212.—Ginkgo biloba: leaf showing bilobed ch
. Morphology of gymnosperms. Gymnosperms; Plant morphology. GINKGOALES 187 VASCULAR ANATOMY The transverse section of the stem of Ginkgo shows the general features of Coniferales, namely, a comparatively narrow cortical zone, a thick and compact cylinder of secondary wood developed by a persistent primary cambium (in contrast with Cycadales), and a relatively small pith (in contrast with Cordaitales). In the dwarf shoots, however, the pith is large and the zone of wood comparatively narrow. The primary xylem is endarch, and there is no distinct. Fig. 212.—Ginkgo biloba: leaf showing bilobed character and dichotomous venation; slightly enlarged.—After Coulter (54). mesarch structure except in the bundles of the cotyledons (20) (fig. 213). The leaf trace is double, as in all the more primitive gymnosperms, each of the strands forking at the base of the blade, and the resulting four strands breaking up into the characteristic dichotomous system of veins, which may show now and then slight traces of centripetal wood, and therefore an indistinct mesarch struc- ture. The vascular anatomy of the seedling has been reviewed by Hill and De Fraine (51), whose summary contains the facts that Ginkgo differs from the cycads in the rotation of the protoxylem of the cotyle- donary traces; that a single vascular strand enters the base of each. 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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