Classification of Gymnosperms

Classification of Gymnosperms

Sporne (1965) classified gymnosperms into 3 classes, 9 orders and 31 families. The classes include i) Cycadospsida ii) Coniferopsida iii) Gnetopsida.

General Characters of Main classes:

Class I – Cycadopsida

•            Plants are palm-like or fern-like.

•            Compound, frond-like pinnate leaves.

•            Manoxylic wood.

•            Sperms are motile.

•            Flower like structures are absent. Strobili are simple.

Example: Cycas, Zamia.

Class II – Coniferopsida

•            Tall trees with simple leaves of varied shape.

•            Wood is pycnoxylic.

•            Cone like strobili are present.

•            Motile sperms are absent (except Ginkgo biloba). Example: Pinus.

Class III – Gnetopsida

•            Shrubs, trees and lianas.

•            Leaves are elliptical or strap-shaped, simple, opposite or whorled.

•            Motile sperms are absent.

•            Wood contains vessels.

•            Strobili is called as inflorescence.

•            Flower like structure with perianth is present. Example: Gnetum, Ephedra.