43 C. Seedless Vascular Plants (Pteridophytes):Vascular plants first appear in the fossil record about 410 million years before present. Development of vascular tissue allowed plants to successfully colonize habitats that until then were not available to them. Xylemis the tissue responsible for water conduction in vascular plants, but also provides support due to its lignified cell walls. The earliest vascular plants were seedless. Although they no longer dominate the present-day landscape, there are still two extant (living) phyla. All have an alternation of generations life cycle, as do the bryophytes, but here, the sporophyte is the dominant generation and the gametophyte is reduced and either free-living or contained within the spore. As you look at representatives of these phyla today, compare them to the bryophytes and observe further adaptations they have made to survive life on land. Most ferns and related plants (Phylum Pterophyta), and some lycopods (Phylum Lycophyta) are homosporous, meaning that:
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