Isotopic studies of plant physiology

Abstract

The system of classification most often used today has been developed through considering the general course of evolution in the plant kingdom. The primary classification is into Divisions as follows:- Division (a) THALLOPHYTA: (The simplest plants, and probably the lowest on the evolutionary scale). These do not have stems, leaves or roots and have only simple reproductive structures. The division thallophyta is further subdivided into ALGAS and FUNGI. Division (b) BRYOPHYTA: (Liverworts and Mosses). Many have plant bodies differentiated into stems and leaves, but all lack vascular tissue (tissue developed to transfer water and soluble food through the plant) The reproductive structures are more highly developed than those of the thallophyta. Division (c) PTERIDOPHYTA: (Ferns and Club Mosses). These possess roots, stems and leaves at some stage in their life cycle, and contain vascular tissue. Division (d) SPERMATOPHYTA: (Highest on the evolutionary scale). Members of this division are the most complex of plants. They possess roots, stems, leaves, have vascular tissue and also produce seeds. The division spermatophyta is further subdivided into GYMNOSPERMS (cone-bearing plants) and ANGIOSPERMS (seed-bearing plants).