The pteridophytes were much more advanced than the bryophytes. While the structure of the
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bryophytes was primarily cellular, that of the fern plant is vascular. Unlike the bryophytes, the pteri-dophytes originate from a fertilized egg and produce spores. Pteridophytes are well represented by the ferns, which have existed from the Devonian period. Another class of pteridophytes is the horsetails (Equisetales), which also have existed from the Devonian to the present.
The third class of pteridophytes is the club mosses, which are largely creeping, many-branched plants with numerous tiny, mosslike leaves spirally arranged on the stem. The final class of pterido-phytes, Sphenophyllales, consisted of slender plants with jointed stems and leaves in whorls. These climbing plants are known from the Devonian to the Permian periods.
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