Plants -Parts and Structural Organization
The main functions of the root system are-
A- absorption of water and minerals from the soil
B- providing a proper anchorage to the plant parts
C- storing reserve food material and synthesis of plant growth regulators.
* The primary roots and its branches constitute the tap root system, as seen in the mustard plant.
* In some plants, like grass, Monstera and the banyan tree, roots arise from parts of the plant other than the radicle and are called adventitious roots.
*The root is covered at the apex by a thimble-like structure called the root cap. It protects the tender apex of the root as it makes its way through the soil.
* Hanging structures that support a banyan tree are called prop roots.
* Similarly, the stems of maize and sugarcane have supporting roots coming out of the lower nodes of the stem. These are called stilt roots.
* The region of the stem where leaves are born are called nodes while internodes are the portions between two nodes.
* Underground stems of potato, ginger, turmeric, zaminkand, colocasia are modified to store food in them.
* Some stems perform the function of storage of food, support, protection and of vegetative propagation.
* A typical leaf consists of three main parts: leaf base, petiole and lamina.
* Leaves originate from shoot apical meristems. Leaf develops at the node and bears a bud in its axil. The axillary bud later develops into a branch.
*The lamina or the leaf blade is the green expanded part of the leaf with veins and veinlets.
* The arrangement of veins and the veinlets in the lamina of leaf is termed as venation.
* When the veinlets form a network, the venation is termed as reticulate. When the veins run parallel to each other within a lamina, the venation is termed as parallel.
* Leaves of dicotyledonous plants generally possess reticulate venation, while parallel venation is the characteristic of most monocotyledons.