Some of them are "altogether of a cycadean
type" (Scott) in respect of the seed. On the other hand, the
Bennettiteae of the Jurassic have the mixed characters of ferns,
cycads, and flowering plants, and thus, in their turn, point
downward to a lower ancestry and upward to the next great stage
in plant-development. It is not suggested that the seed-ferns we
know evolved into the cycads we know, and these in turn into our
flowering plants. It is enough for the student of evolution to
see in them so many stages in the evolution of plants up to the
Angiosperm level. The gaps between the various groups are less
rigid than scientific men used to think.
Taller than the cycads, firmer in the structure of the wood, and
destined to survive in thousands of species when the cycads would
be reduced to a hundred, were the pines and yews and other
conifers of the Jurassic landscape. We saw them first appearing,
in the stunted Walchias and Voltzias, during the severe
conditions of the Permian period. Like the birds and mammals they
await the coming of a fresh period of cold to give them a decided
superiority over the cycads. Botanists look for their ancestors
in some form related to the Cordaites of the Coal-forest.
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