Triphyletic evolution of vascular plants

Abstract

Permian Shansi flora reveals the relation between the change of plants and the environments which is shown in the principles of Growth Retardation (abbreviated G. R.). The changes of plants in Palaeozoic, Mesozoic and Cenozoic are all explained by the principles of G. R., not by the principles of Growth Acceleration, which means that the environments in geological age must have been changed to the more and more unsuitable environments for the growth of plants. These environmental changes indicate the palaeoclimatic change of increasing annual range of temperature. To adapt to these climatic changes the plants might have to change successively their form and function through geological age. We call these changes - evolution. Therefore the plants might have to change their form and function grading up from spore-stage (pteridophyte) to angiosperm-stage through gymnosperm-stage.

Palaeozoic pteridophytes have three lineages, namely, Lycopsida (have microphyll), Sphenopsida (have articulate stem) and Pteropsida (have macrophyll). The plants of these three lineages in Palaeozoic must have changed parallelly their form and function grading up from spore-stage to angiosperm-stage through ages. Therefore it is reasonable to recognize the evolution of three lineages, Microphyta, Arthrophyta and Macrophyta.