Classification of Gymnosperms

K.R. Sporne in 1962 classified the whole gymnosperms into three classes and they are again divided into orders.
i. Cycadopsida
Orders: Pteridospermales, Bennettiales, Pentoxylales, Cycadales
Cycas revoluta
  • Primitive group, represented by small plants.
  • Wood is manoxylic
  • Male cones are large with compactly arranged microsporophylls
  • Megasporophylls are loosely arranged does not form a cone.
  • Seeds are  radially symmetrical
  • Examples: Cycas, Zamia
ii. Coniferopsida
Orders: Cordaitales, Coniferales, Ginkoales and Taxales
Pinus male cone
    Gnetum
  • Includes larger dominant gymnosperms.
  • Wood is pycnoxylic
  • Sporophylls form cones.
  • Seeds are bilaterally symmetrical.
  • Examples: Pinus, Taxus, Ginko
iii. Gnetopsida
Orders: Gnetales
  • Includes advanced gymnosperms.
  • Secondary xylem shows vessels.
  • Ovules are orthrotropous with long tubular micropyle.
  • Examples: Gnetum , Ephedra, Welwitschia
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