In this article we will discuss about the classification of psilophytopsida. The Psilophytopsida comprise of the fossilised ancient Silurian-Devonian order Psilophytales. The discovery of the different genera from such wide places as Canada, Scotland, Europe and Australia shows that these plants were of world-wide distribution in those days. The Psilophytopsida and the living Psilotopsida have been included within a single [...]
In this article we will discuss about the two principal types of stelar organisation in vascular plants: 1. Protostele 2. Siphonostele. Type # 1. Protostele: It is the simplest and most primitive type of stele. The vascular cylinder consists of solid core of xylem surrounded by phloem, pericycle and endodermis. There is no pith e.g., Selaginella, Lycopodium, Lygodium, Gleichenia etc. [...]
The following points highlight the three classes of Pteridophytes. The classes are: 1. Psilopsida 2. Lycopsida 3. Sphenopsida. Pteridophytes: Class # 1. Psilopsida (Psilophytes): They are the most primitive vascular plants. Roots are absent. Instead rhizoids occur. Stem is dichotomously branched. It has two parts, aerial and rhizomatous. Aerial stems are green and photosynthetic. Leaves may be present or absent. [...]