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.