Introduction to Telome Theory: It is now widely accepted (on the basis of overwhelming amount of evidence) that the land- dwelling plants evolved from aquatic ancestors. Ail organisms known in the Precambrian, Cambrian and Ordovician periods of Paleozoic Era lived in aquatic environment. The evolutionary conquest of land probably occurred sometimes between the late Cambrian and early Silurian. The concrete [...]
In this article we will discuss about the structure of Lycopodium with the help of diagrams. The main plant body is sporophytic. It consists of slender and branched stem, numerous small leaves (microphylls) and dichotomously- branched roots (Fig. 7.23A, B). Roots: The primary root or first formed root of the young sporophyte is ephemeral, short-lived. The older plants have dichotomously [...]
In this article we will discuss about:- 1. History of Heterospory 2. Incipience of Heterospory 3. Origin 4. Evidences 5. Advantages. History of Heterospory: Pteridophytes are the first true land plants. Being the first successful colonisers in land habit pteridophytes show both the homospory and heterospory. Most of the pteridophytes are homosporous, produce isospores which are morphologically and physiologically identical. [...]