Plants
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Plants Main Page |
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Special Segments
General Topics
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The phylum Tracheophyta is an extremely large and diverse group and contains almost all of the terrestrial plants, or what people consider plants. The group probably arouse in the early Silurian with the evolution of a remarkable new cell type, the tracheid. These tracheids strung together provided plants with a plumbing system (vascular system) that allowed water and nutrients to be moved through the plant. This innovation is important because it provided a route for the long-distance movement of water and nutrients from a source to where they were needed and it also served as a structural support system. These two functions allowed plants to adopt a truely terrestrial existence. The Tracheophyta (or vascular) plants can be divided as below. A great deal of disagreement exists among botanists about both the names and the levels of the higher classification of the vascular plants. The one used below follows Pearson, L. C. 1995. The Diversity and Evolution of Plants. CRC Press. New York. Other commonly or more familiar names are given in parentheses.
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