. Evolution of plants . Mesozoicvegetation. As it is this class of plants whichhas come to be of chief interest in consideringthe question of the evolution of Angiosperms,we must discuss them rather fully, especiallyas they are not very familiar plants except tobotanists. The Cycads have not been so much dimin-ished in the course of ages as the family of theMaidenhair-tree, though, in proportion, perhaps,the reduction is not much less. They are repre-sented at present by a small family, the Cyca-dacea?, which includes nine genera and about100 species. They are handsome plants, withfoliage not
. Evolution of plants . Mesozoicvegetation. As it is this class of plants whichhas come to be of chief interest in consideringthe question of the evolution of Angiosperms,we must discuss them rather fully, especiallyas they are not very familiar plants except tobotanists. The Cycads have not been so much dimin-ished in the course of ages as the family of theMaidenhair-tree, though, in proportion, perhaps,the reduction is not much less. They are repre-sented at present by a small family, the Cyca-dacea?, which includes nine genera and about100 species. They are handsome plants, withfoliage not unlike that of some Palms, whencetheir popular name, Sago-palms, for a kind ofsago is obtained from some of them. With thetrue Palms, however, they have nothing whateverto do. Some few are often met with in cultiva- THE EVIDENCE 59 tion under glass, but it is only in botanic gardensthat they are to be seen in any numbers. Thereis a magnificent collection at Kew, chiefly in thePalm-house. They are natives of the tropical. Fig. 1.—Male plant of Stangcria schizodon, bearing severalcones. Kew. and sub-tropical regions of the earth. Of thenine genera, one, the type-genus Cycas (fig. 6,)18 common to Asia and Australia; two, Macro-zamia (figs. 2 and 3) and Bowenia, are Australian;two, Encephalartos and Stangeria (fig. 1), areSouth African; while four, Zamia, Ceratozamia, CO THE EVOLUTION OF PLANTS Dioon, and Microcycas (fig. 4), are American, thelast-named, containing a single species, havingonly been found in the island of Cuba. Thefamily is thus widely distributed, though itsmembers are not often met with in great abund-ance. In a few cases the living Cycads attain thestature of trees. Microcycas (in spite of its name,which means little Cycad) grows to a height of30 feet; a species of Dioon, from Mexico, attains40 feet, and an Australian species of Cycas issaid to reach as much as 60 feet in height. Somespecies of Encephalartos, when old, have thecharacter of low trees. In most sp
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