. Morphology of gymnosperms. Gymnosperms; Plant morphology. BENNETTITALES 77 which project only i. 5 cm. beyond the disk, each bearing two lat- eral rows of synangia along the rachis. This remarkable "reduction" of the stamen set, as compared with that in Cycadeoidea, has inten- sified the suggestion of an angiosperm connection. That the stamens of Bennettitales bore synangia of the ordinary Marattia type (fig. 61) has been shown to be true of all the forms. Fig. 61.—Cycadeoidea dacotensis: part of transverse section through unexpanded microsporophyll, showing synangia with loculi ar
. Morphology of gymnosperms. Gymnosperms; Plant morphology. BENNETTITALES 77 which project only i. 5 cm. beyond the disk, each bearing two lat- eral rows of synangia along the rachis. This remarkable "reduction" of the stamen set, as compared with that in Cycadeoidea, has inten- sified the suggestion of an angiosperm connection. That the stamens of Bennettitales bore synangia of the ordinary Marattia type (fig. 61) has been shown to be true of all the forms. Fig. 61.—Cycadeoidea dacotensis: part of transverse section through unexpanded microsporophyll, showing synangia with loculi arranged in two rows; some of the loculi contain pollen grains; X25.—After Wieland (22). examined, including the older known European species. The struc- ture of the synangia seems to be almost identical with those of Marattia or of Danaea (fig. 62). Superficially there is a wall of heavy cells, and between it and the sporangial chambers there is a more delicate tissue. The sporangial chambers are separated from one another by partitions consisting each of a single plate of cells, and form two rows, between which the synangium dehisces in two valves. It is evident that this structure has advanced little beyond the fern level, and might well belong to Cycadofilicales or to Filicales. In fact, the free portion of a microsporophyll, if detached, would certainly be mistaken for a Marattia-like fern. This relatively stationary character of the microsporangiate structures appears throughout 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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