Classification of Gymnosperms

Sporne (1965) classified the gymnosperms into three classes spanning nine orders and thirty-one families. Cycadopsida (e.g. Cycas, Zamia) are palm-like or fern-like plants with compound, frond-like pinnate leaves, manoxylic wood, motile sperm, and no flower-like structures — their strobili are simple. Coniferopsida (e.g. Pinus) are tall trees with simple leaves of varied shape, pycnoxylic wood, and cone-like strobili; motile sperm are absent in this class except in Ginkgo biloba. Gnetopsida (e.g. Gnetum, Ephedra) include shrubs, trees and lianas with elliptical or strap-shaped, simple, opposite or whorled leaves; motile sperm are absent, the wood contains vessels (unlike …