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Plants evolved more than 430 million years ago from multicellular green algae. By 300 million years ago, trees had evolved and formed forests, within which the diversification of vertebrates, insects, and fungi occurred. Roughly 266,000 species of plants are now ....

Middle of Essay
.... crossing. Many angiosperms display other modes of pollination, including self-pollination. Evolutionary Origins Plants derived from an aquatic ancestor, but the evolution of their conducting tissues, cuticle, stomata, and seeds has made them progressively less dependent on water. The oldest plant fossils date from the Silurian Period, some 430 million years ago. The common ancestor of plants was a green alga. The similarity of the members of these two groups can be demonstrated by their photosynthetic pigments (chlorophyll a and b,) carotenoids); chief storage product (starch); cellulose- rich cell walls (in some green algae only); and cell ....