. The elements of botany embracing organography, histology, vegetable physiology, systematic botany and economic botany ... together with a complete glossary of botanical terms. Botany. PTEBIDOPHYTA. 153 PTERIDOPHYTA. i77rThe sixth division, called Pteridophyta, include tlie Ferns (Fig. 265) and their allies. Here, as in the previous division, there is an alternation of sexual and non-sexual generations. But while the conspicuous gen- eration (the Moss) in the Bryophyta is sexual (and the inconspicuous, namely, the sporangium, non-sexual), the reverse is the case in the Pterido- phyta, that is
. The elements of botany embracing organography, histology, vegetable physiology, systematic botany and economic botany ... together with a complete glossary of botanical terms. Botany. PTEBIDOPHYTA. 153 PTERIDOPHYTA. i77rThe sixth division, called Pteridophyta, include tlie Ferns (Fig. 265) and their allies. Here, as in the previous division, there is an alternation of sexual and non-sexual generations. But while the conspicuous gen- eration (the Moss) in the Bryophyta is sexual (and the inconspicuous, namely, the sporangium, non-sexual), the reverse is the case in the Pterido- phyta, that is, the conspicuous generation (the Fern, etc.) is non- sexual ; and the sexual generation, or stage, bearing the sexual repro- ductive organs (the prothallium) is very much reduced and short- lived. This prothallium is a small, flattened, thallus-like growth from the spore, composed of chlorophyll- bearing parenchymous cells, in one or a few layers; on its under sur- face are produced rhizoids, by which it is fixed to the ground. On the prothallia are developed the arche- gonia and antheridia, which are essentially similar to those in the higher plants of the pre- ceding division. The spirallj-coiled spermatozoids escape from the antheridium, enter the tube, or neck, of the archegonium, and fertilize the germ-cell therefn con- tained. The result of this is the formation of a young plantlet, which develops into a leafy plant of considerable size, with marked differentiation of tissue, and capable of producing non-sexual spores. Fig. 205. A Fern (Camptosorus rhizophyllus'j; fr, frond; sor, sori; in, indu- sium ; spn, sporangium; spo, 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 Kellerman, William Ashbrook, 1850-1908. Philadelphia, J. E. Potter and Company
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectbotany, bookyear1883
