. Morphology of gymnosperms. Gymnosperms; Plant morphology. GNETALES 373. 415 In Welwitschia the flowers are functionally monosporangiate and dioecious, but the staminate flowers are structurally bisporangiate (figs. 415, 416). They are borne in the axils of broad and closely over- lapping bracts, whose decussating pairs form a conifer-hke strobilus (figs. 417, 418). These strobili are produced upon branching axes which arise from the crown above the foliage leaves, or rarely beneath them. Pear- son (20), from a field study of Wel- witschia, states that it is probably partially if not wholly p
. Morphology of gymnosperms. Gymnosperms; Plant morphology. GNETALES 373. 415 In Welwitschia the flowers are functionally monosporangiate and dioecious, but the staminate flowers are structurally bisporangiate (figs. 415, 416). They are borne in the axils of broad and closely over- lapping bracts, whose decussating pairs form a conifer-hke strobilus (figs. 417, 418). These strobili are produced upon branching axes which arise from the crown above the foliage leaves, or rarely beneath them. Pear- son (20), from a field study of Wel- witschia, states that it is probably partially if not wholly pollinated by insects, a statement which finds addi- tional confirmation in the fact that just below the anthers there are glan- dular protuberances which, in sections, may be interpreted as nectaries (fig. 415. 0- The staminate flower consists of two decussate pairs of free bracts, within which there is a whorl of six (rarely five or four) monadelphous stamens, each of which bears a terminal peltate group of three sporangia arranged in an approximately circular synangium. In the center there is a single sterile ovule whose projecting micropylar tube is spirally coiled and ends in a broad flaring expansion (figs. 415, 416). It is very evident that the immediate ancestors of Welwitschia had bispo- rangiate flowers, a feature completely ehminated from most of the gymno- sperms, if they ever possessed it. The only other g)minosperms that possess it are the Bennettitales, and they are. 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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