. The origin of a land flora, a theory based upon the facts of alternation. Plant morphology. $N s^.. (f^sp ( '-* V. Fig. 85. Botrychium Limaria. Sterile laminae, which occasionally produce sporangia (sp) on certain pinnae, and have partly CO, wholly assumed the form of the fertile spike : yin B and C is the fertile spike itself. itfatural size. (After Goebel.) exact in the arrangement and in the time of origin of their sporangia. Such precision is seen in higher degree in the Calamarians and Spheno- phylls, and it is specially prominent in the Lycopods. All of these are types of quite as
. The origin of a land flora, a theory based upon the facts of alternation. Plant morphology. $N s^.. (f^sp ( '-* V. Fig. 85. Botrychium Limaria. Sterile laminae, which occasionally produce sporangia (sp) on certain pinnae, and have partly CO, wholly assumed the form of the fertile spike : yin B and C is the fertile spike itself. itfatural size. (After Goebel.) exact in the arrangement and in the time of origin of their sporangia. Such precision is seen in higher degree in the Calamarians and Spheno- phylls, and it is specially prominent in the Lycopods. All of these are types of quite as early, probably of even earlier, geological history than the Leptosporangiate Ferns. Accordingly it may be held that in the earliest Vascular Plants which we know the arrangement, time of appear- ance, and number of the sporangia showed some degree of definiteness, and were in some cases very precise. It cannot be denied that accessory sporangia may at the present day appear in some cases where none are normally present: conspicuous examples are those described by Lang in apogamous Ferns (compare Fig. 35), while a less bizarre case is that of the sporangia which appear on the usually sterile leaf of Botrychium Lunaria (Fig. 85): abnormal flowers of Phanerogams also provide numerous examples of sporangia not produced in the usual order or position. The question is whether the existence of such cases at 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 Bower, F. O. (Frederick Orpen), 1855-1948. London, Macmillan and Co. , Ltd.
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