In this article we will discuss about the evolution of stele in a plant. Stele (= Greek word meaning a column) can be defined as the unit of vascular system that is made up of xylem, phloem, interfascicular tissues, medullary rays, pericycle and pith (if present). The term stele refers to the central core of plant axis and is restricted [...]
In this article we will discuss about the evolution of stelar forms in vascular plants. The well known genus Rhynia represents the simplest kind of vascular plant. It is rootless, leafless and the axis is dichotomously branched. A stele runs through the centre of stem. The cells in the very centre of stele consist of tracheids only and this xylem [...]
In this article we will discuss about the four main types of root stem transition in angiosperms. Type A (Fig. 16.1.1A-1E): This type is represented by Dipsacus, Mirabilis and Fumaria. In the root there are four strands of phloem and four strands of xylem with exarch protoxylem. They are arranged radially. The stem shows four conjoint collateral vascular bundles with [...]