Structure and Function of Root

Morphological structure is a picture of the outside of the body of an organism. The structure of higher plants, such as Angiosperm and Gymnosperm can be described as follows. Morphological structure of higher plants generally consist of roots, stems, and leaves. At a certain stage in its development, plants can form flowers, fruits and seeds. The structure of plant morphology Angiosperm group is related to the condition of the environment in which his life. At the same time, plants have to extract resources from the land and air. Water and minerals from the ground, while the air is where the availability of CO2 and sunlight can not penetrate the soil. Therefore, the plant has a root system under the ground and shoot system is above ground level. Each system need each other.
The roots are usually found in the soil, not jointed-books, the color is not green, and ends usually grows steadily. Roots function to (i) strengthen the establishment of plants, (ii) to absorb water and minerals from the soil, and (iii) sometimes serves as a place to store food reserves.


A. ROOT MORPHOLOGY STRUCTURE

Based on the origin of the formation, the roots can be divided into the primary root and adventitious roots. Primary roots formed from the ends of the embryo and from pericycle, whereas adventitious roots growing from the roots that have grown apart from pericycle or out of other organs such as leaves and stems. There are two types of root systems, namely taproot and fibrous roots. Taproot found in dicotyledonous plants and plant seeds open, and the root fibers found in monocotyledonous plants. Taproot has one large main roots, whereas in monocotyledonous plants such as root fibers, in the form of hairs or fibers and are relatively the same.






In taproot, root base usually consists of a root that is continuous with the root base of the stem, root tip, which is the root of most young, consisting of tissue that can still hold the growth, which is the root of the root stem located between the base of the root and ends, and branches of the root, which is part of the root that are not directly continuous with the base of the stem and roots out of the trunk, the branches root root fibers are silky-smooth and shaped fibers, root hairs that the root of a very delicate role to absorb water and minerals, and root cap, that the roots are located at the far end.

Types of roots can be modified according to the place of growth. Some plants store food reserves in parenchyma cells of root cortex, such as carrots.



In plants that live in dry and arid regions, the roots can be used as a place to store water. In the mangrove plants and some plants that live in water, its roots are modified to form pneumatofor to help supply oxygen to the roots submerged in water. At the the banyan tree formed support root that supports the establishment of plants.

B. STRUCTURE ANATOMY OF ROOTS

At the root, there are four regions (zones) are different, namely differentiation zone, maturation zone, elongation zone, and division zone. Maturation zone consists of cells that are actively dividing and protected by the root cap. In division zone, the root hairs and secondary root are grows.

At the root of the transverse incision, from the outside in common: the epidermis, cortex, endodermis, and a cylindrical center. The exterior of the cylindrical form perisikel center, and inside there are files vessels consisting of xylem and phloem are arranged radially.

The outermost layer of the root is the epidermis. The epidermis covering the outer surface of the root. In areas of maturation, the epidermis forming root hairs that serve to broaden the field of water and mineral uptake. In the maturation zone, root hairs are dead. Epidermal cells are newly formed in the elongation zone and subsequent elongation zone and the maturation zone evolved into a re-formed root hairs. Thus, the roots must continually experienced growth root hairs that remain available for absorption of water and minerals. Old epidermis serves to protect the roots. Epidermal cell structure is meeting without the space between cells, and thin-walled. The cell wall is composed of cellulose and pectin material. Root epidermis is usually composed of a single layer of cells.

Root cortex consists of parenchyma tissue is relatively loose that met certain amount of space between cells and serves to provide air for cell respiration. Parenchymal tissue in the cortex can also serve as a place to store starch. On the inside layer of the epidermis is often contained a layer or multiple layers of cells form a dense tissue called the hypodermic or that cell wall containing suberin and lignin.

Endodermis is a layer of cells that continued to form cylindrical or ring and separate the cortex from the carrier beam next to it. The walls in the endodermis cells form a the ribbon kaspari, which is a thickening of suberin and lignin in the cell wall and causes radial region between endodermis cells are impermeable to water. The existence of the ribbon kaspari causing all the water that passes through the endodermis, must go through the endodermis cells and not between the cells. In this way endodermis cells can control the movement of water into the vascular tissue and prevent the movement of water back to the cortex.

Cylindrical center or stele at the roots form on the inside of the endodermis. The exterior consists of one or more cells called pericycle (pericambium), which is responsible for the formation of lateral roots, where the vascular cambium, cork cambium and was instrumental in the process of thickening.

C. FUNCTION OF ROOTS

The main function of root is to absorbs the water and minerals dissolved in it from the ground. To support this function, the root equipped with root hairs, which function to broaden the root surface area. The other root function is to construct the body of plant. Besides, there is a particular function of root, which can only be found in several certain plants, such as to keep the food reserve in cassave, as vegetative reproductive organ in dahlia, as respiratory organ in aerial root of orchid and weeping fig tree, prop roots of mangrove plants.