. The origin of a land flora, a theory based upon the facts of alternation. Plant morphology. SCHIZAEACEAE 549 bearing on this the development of its seedling does not suggest reduction from any more complicated type. In the seedling of Aneimia there is at first a solid stele, which is converted into a dialystelic one by gradations similar to those for instance in Pteris: the ontogeny may here be held to indicate the probable evolutionary progression. In the case of Schizaea. Fig. 307. Transverse section of axis of seedling of Lygodiumjaponicum, below the first leaf, p = one of the xylem-paren
. The origin of a land flora, a theory based upon the facts of alternation. Plant morphology. SCHIZAEACEAE 549 bearing on this the development of its seedling does not suggest reduction from any more complicated type. In the seedling of Aneimia there is at first a solid stele, which is converted into a dialystelic one by gradations similar to those for instance in Pteris: the ontogeny may here be held to indicate the probable evolutionary progression. In the case of Schizaea. Fig. 307. Transverse section of axis of seedling of Lygodiumjaponicum, below the first leaf, p = one of the xylem-parenchyma cells. X390. (After Boodle.) the facts indicate that its middle position is due to amplification of the stele leading up towards the solenostelic state, though the opinion is also a tenable one that the genus illustrates phases of reduction. Embryology. This is described as being similar to that common for most Ferns in the case of Schizaea pusilla} It may be noted, however, that the fila- mentous prothallus in this species shows very close analogies with that of the Hymenophyllaceae. In discussing the probable phyletic relations of the living Schizaeaceae, Prantl 2 remarks that it is impossible to derive any one genus from any other : they have obviously similar soral and sporangial characters, but they differ so greatly one from another in other respects that we can only regard them as derived from some simpler type, which may be held as a common 1 Britton and Taylor, , p. 2. , p. 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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