Cycads, a group of the gymnospermous division of the phasnogamous or flowering plants, apparently beginning near the close of the carboniferous age, passing their climax in the Jurassic period, and thence gradually declining to the present time. Though related to the coniferous trees in structure and fructification, they are entirely different in habit; they have a simple trunk, with a tuft of large leaves or fronds at the top, resembling a tree fern or a young palm. The fronds unroll in expanding, as in the ferns, but their form resembles palm leaves, though there is no tendency to split longitudinally. They are sometimes 30 ft. high, while the allied genus zamia rarely exceeds 3 or 4 ft. They are at present confined to warm regions: the West Indies, Mexico, equatorial South America, southern Africa, Madagascar, southern Asia, Japan, the East Indies, and Australia. They are especially a mesozoic type, having the retrospective features of the palaeozoic ferns and the prospective characters of the cretaceous palms.

Cycadoidea megalophylla   Cone and Leaf.

Cycadoidea megalophylla - Cone and Leaf.