. The origin of a land flora, a theory based upon the facts of alternation. Plant morphology. 124 VARIATIONS IN NUMBER OF SPORANGIA morphology of Vascular Plants ; while the regularity and constancy in number and position of the sporangia in the Lycopods, Equiseta, and Eusporangiate Ferns, in which interpolation does not occur, has been underestimated. But these, on grounds of comparison, and of fossil history, are among the most primitive of Vascular Plants. Thus interpolation of new sporangia is to be recognised as an actual factor of increase in number of sporangia, but it is not a general

. The origin of a land flora, a theory based upon the facts of alternation. Plant morphology. 124 VARIATIONS IN NUMBER OF SPORANGIA morphology of Vascular Plants ; while the regularity and constancy in number and position of the sporangia in the Lycopods, Equiseta, and Eusporangiate Ferns, in which interpolation does not occur, has been underestimated. But these, on grounds of comparison, and of fossil history, are among the most primitive of Vascular Plants. Thus interpolation of new sporangia is to be recognised as an actual factor of increase in number of sporangia, but it is not a general Stock Photo

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. The origin of a land flora, a theory based upon the facts of alternation. Plant morphology. 124 VARIATIONS IN NUMBER OF SPORANGIA morphology of Vascular Plants ; while the regularity and constancy in number and position of the sporangia in the Lycopods, Equiseta, and Eusporangiate Ferns, in which interpolation does not occur, has been underestimated. But these, on grounds of comparison, and of fossil history, are among the most primitive of Vascular Plants. Thus interpolation of new sporangia is to be recognised as an actual factor of increase in number of sporangia, but it is not a general phenomenon, and there is reason to. 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 work.. Bower, F. O. (Frederick Orpen), 1855-1948. London, Macmillan and Co. , Ltd.

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RMRDXFW9–. The origin of a land flora, a theory based upon the facts of alternation. Plant morphology. . 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 work.. Bower, F. O. (Frederick Orpen), 1855-1948. London, Macmillan and Co. , Ltd.

RMRDXGWF–. The origin of a land flora, a theory based upon the facts of alternation. Plant morphology. . 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 work.. Bower, F. O. (Frederick Orpen), 1855-1948. London, Macmillan and Co. , Ltd.

RMRDXGXB–. The origin of a land flora, a theory based upon the facts of alternation. Plant morphology. . 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 work.. Bower, F. O. (Frederick Orpen), 1855-1948. London, Macmillan and Co. , Ltd.

RMRDXMRH–. The origin of a land flora, a theory based upon the facts of alternation. Plant morphology. . 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 work.. Bower, F. O. (Frederick Orpen), 1855-1948. London, Macmillan and Co. , Ltd.

RMRDXMRK–. The origin of a land flora, a theory based upon the facts of alternation. Plant morphology. JUNGERMANNIALES 267 clue to the steps of evolution of the elaterophore: that it arose by partial sterilisation of the archesporium, with the consequence that the fertile zone is relegated to the exterior. The development in Pellia is essentially the sarne, but the attachment of the elaterophore is to the base of the capsular cavity. It is worthy of note that these modifications occur in the Anakrogynous Jungermanniaceae, which, as we have already seen, are more advanced than the Akrogynous as regards

RMRDXG74–. The origin of a land flora, a theory based upon the facts of alternation. Plant morphology. 322 LYCOPODIALES is doubtful what is the evolutionary relation between the distal and the basal insertion of the sporangium upon the sporophyll ; whether the one or the other is the more primitive in the Lycopodiales must be left for the present open, but it is evident that such differences as these are of degree only, in a type which is constant as regards the numerical relation of the sporangia to the sporophylls, and in the coincidence of the median planes of both of those parts. There seems little

RMRDXF57–. The origin of a land flora, a theory based upon the facts of alternation. Plant morphology. MARATTIACEAE 52S It will be unnecessary to describe it in detail here: our object will be rather to bring it into relation with the less complex systems of other Ferns, and with the cognate fossils. This is most readily done by reference to the seedling-structure, and to those genera which are less complicated in their mature state ; for there is considerable variety of complexity in the different living genera of the family. It is found that Kaulfussia and Archangiopteris are relatively simple, while

RMRDXFD6–. The origin of a land flora, a theory based upon the facts of alternation. Plant morphology. Fjq.l.. Fiq. 3. [ 11 : I . *V if Ey.5.-Mfl's ' | If '' S^. 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 work.. Bower, F. O. (Frederick Orpen), 1855-1948. London, Macmillan and Co. , Ltd.

RMRDXETN–. The origin of a land flora, a theory based upon the facts of alternation. Plant morphology. CYATHEAE 607 by a diagrammatic figure (Fig. 338), but with the reservation that the rapidity with which the successive stages are passed through varies considerably : it is believed, however, that the diagram will serve to represent the course of development of the vascular system, not only in the Cyatheae, but also in most of the solenostelic and dictyostelic Ferns, up to the particular stage that they retain when mature. The following description is taken almost verbally from Mr. Gwynne-Vaughan's me

RMRDXFXT–. The origin of a land flora, a theory based upon the facts of alternation. Plant morphology. SPORE-PRODUCING MEMBERS 377 in the middle of the internode (Fig. 202), and in Stachannularia or Cingularia at the top of the internode (Fig. 204). Such facts as these, here only briefly sketched, must be taken into account in discussing the morphology of the strobilus of the Equisetales, and in deciding the true chararacter of the sporangiophores. But before this is entered upon their detailed structure and development must be examined. Spore-Producing Members. Naturally the development of the spore-p

RMRDXN11–. The origin of a land flora, a theory based upon the facts of alternation. Plant morphology. 146 SPORANGIOPHORES AND SPOROPHYLLS the same median plane, and, excepting rare abnormalities, each sporophyll subtends only one sporangium: this is seen in all .plants belonging to the Lycopodiales. But they illustrate various degrees of remoteness of the sporangium from the axis, while still retaining the strict numerical and subtending relation. Thus Selaginella shows the closest relation of the sporangium to the axis; but the sporangium of Lycopodium originates clearly from the tissue of the sporop

RMRDXG3M–. The origin of a land flora, a theory based upon the facts of alternation. Plant morphology. 346 LYCOPODIALES to its base: it is clear that the relation of the apex to the intersection of the first walls has been a close one (Fig. 183 a). The axis soon proceeds to form successive leaves spirally arranged. The cotyledon and subsequent leaves have the ordinary characters of the foliage leaves of the species. The tissue below soon becomes elongated as the hypocotyl, the length of which is determined by the level at which the prothallus lies in the soil: where it is at or near to the surface the