Let us learn about Roots. After reading this article you will learn about: 1. Categories of Root 2. General Characteristics of the Roots.
Categories of Root:
(1) Primary, normal roots, which originate from the embryo and usually persist throughout life, and
(2) Adventitious roots, which arise secondarily from stem, leaf or other tissues and which may be either permanent or temporary.
The functions of the primary roots are to anchor the plant in the soil, to absorb water and soluble substances and to serve as storehouses of food materials. The functions of adventitious roots are very various. Sometimes they enter the soil and act as primary roots. In other cases they may be modified into climbing organs, stilts or props, thorns, haustoria, etc.
The anatomy of roots is in many respects simpler than that of stems and it is considerably more uniform, perhaps as the result of a rather uniform environment underground, which is in marked contrast with the extreme variability of the conditions affecting aerial shoots.
Root anatomy is more ancient in type than that of stems. Roots preserve, in their primary condition, the actinostely of the vascular tissues, which in the lower Pteridophyta is characteristic of both stems and roots.
General Characteristics of the Roots:
1. The roots possess a tendency to grow downwards or sideways rather than upwards.
2. There is absence of chlorophyll in the roots.
3. The roots are not susceptible to the influence of light.
4. There is absence of leaves and hence, of course, absence of buds.
5. The roots possess a root cap over the apex.
6. They possess endogenous origin and branching.
7. In roots, the phloem and xylem are situated on different radii in the primary structure.
8. There is a relatively short zone of growth at the apex.
9. They possess root hairs near the apex.