The classification of gymnospermous plants

Abstract

Various systems of classification of the gymnospermous plants are briefly reviewed. Arnold's classification (Bot. Gaz., 1948) is tentatively modified as follows: Division: Cycadophyta- Class 1. Pteridospermopsida, Orders: 1. Lyginopteridales, 2. Medullosales, 3. Glossopteridales, 4. Peltaspermales, 5. Corystospermales, 6. Caytoniales; Class 2. Cycadopsida, Order: 7. Cycadales; Class 3. Pentoxylopsida, Order: 8. Pentoxylales; Class 4. Cycadeoideopsida, Order 9. Cycadeoideales. Division: Chlamydospermophyta- Class Gnetopsida, Orders: 1. Gnetales (restricted to Gnetum), 2. Welwitschiales. Division: Coniferophyta- Class 1. Coniferopsida, Orders: 1. Cordaitales. 2. Ginkgoales; 3. Coniferales; Class 2. Ephedropsida. 4. Ephedrales; Class 3. Czekanowskiopsida. Order: 5. Czekanowskiales; Class 4. Taxopsida. Order: 6. Taxales. The position of the Pentoxylales, Ephedrales, Glossopteridales and Czekanowskiales is discussed in the light of recent research.