THE EVOLUTION OF PLANTS
green or chlorophyll. They appear to be algae that have permanently lost this substance, but we do not yet know enough to speak with assurance as to the origin of the fungi.
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Fig. 1.—At the left, a brief outline of the history of plant classification. At the right, a genealogical tree indicating that the modern groups of plants were descended by evolution, not one from the other, but from preëxistent ancestors, which were also genetically related. This conclusion is based upon a study of the structure (morphology) of existing plants, the life-histories of individual plants (ontogeny), and a comparative study of the morphology of fossil plants (palaeontology or palaeobotany) and modern plants (botany). (From the label for the Evolution Group at the Brooklyn Botanic Garden.)
In contemplating this exhibit, or the plant kingdom itself, here represented in miniature or by samples, one is impressed by the fact that, amid the endless diversity of plant forms, it is possible to bring order out of apparent chaos. Men have been trying to do this with plants for more than two thousand years. What a long, hard struggle it has been to try to understand Nature! About 300 B.C. Theophrastus, a
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