How many Types and Kinds of Roots

1. Fiber Root

The taproot is the primary root or institutional root that continues to grow and lengthen. These roots will become the main roots that support the erection of the plant and in its development form smaller root branches.

This type of fibrous root is found in a monocot plant. But there are also dicotyledonous plants that can also have it (these dicotyledonous plants are propagated in two ways, namely by grafting or by cuttings). The main function of fibrous roots is to be able to strengthen the establishment of a plant.

2. Taproot

Fibrous roots are roots that arise from the base of the stem as a substitute for primary roots or dead institutional roots. Tap and fibrous root systems, each root can be branched to expand the absorption area and to strengthen the establishment of the plant.

This type of root is usually found in a dicotyledonous plant. The taproot has the main function of storing food. Examples are: carrots, sweet potatoes and others.

Other types of roots, namely adventitious roots include:

1. Hanging

The root is a type of root that grows from the top of the stem and grows towards the ground. The hanging roots are seen hanging in the air. This hanging root has a function that is to absorb water vapor and a gas in the air. However, if the hanging roots have reached the ground, the hanging roots will enter the soil and are useful for absorbing water and mineral salts in the soil. Plants that have hanging roots, for example, are banyan trees.

2. Breath Roots

This type of root grows out of the stem at the bottom. The roots of the breath usually appear partly on a soil surface and some are partially underground. These roots can look like they are supporting upright on a stem. The root of the breath has many openings for the entry of air. So that the root of the breath has a function, namely to breathe. Plants that have breath roots, for example, are mangroves and pandanus.

3. Adhesive

Roots Adhesive roots are one type of root that grows along the stem. This adhesive root is in a plant that grows up. Adhesive roots have a function, namely to attach the stem to a wall or other plant. One example of a plant that has sticky roots is the betel plant.

3. Primary Root

Primary roots are roots that continue to grow bigger and elongated, these roots will become the main supporting roots. Primary roots are also known as taproots and institutional roots.

Roots in plants have basic functions, including:

1. Propagating plants in the soil
2. Absorbs water and minerals from the soil
3. Distributing ingredients
4. Spare food storage organs

Primary root structure

The structure and development of roots is in many ways similar to that of stems. If the stem has primary and secondary growth as well as the roots. Primary growth in dicot roots causes the roots to grow lengthwise into the soil.

While secondary growth in dicotyledonous roots contains cambium which causes diameter enlargement. Primary growth in roots depends on the root tip where that part is surrounded by cap-shaped cells and is called the root cap. At the time the roots penetrate the particles in the soil. The root tips are protected by a root cap against mechanical damage. In most dicotyledonous plants, both the root epidermis and the root cap are derived from the outermost layer of tip meristem cells.

In young tissues of dicotyledonous plants root development involves the development of specialized and undifferentiated cells into mature cells as well as specialized cells that play various roles in root activities.

There are 3 main areas that play an important role in the maturation area, namely: vascular cylinder, cortex, and epidermis. In the center of the root there is a vascular cylinder which is built by a network of vessels together with parenchyma. The thick-walled xylem cells carry water and minerals. While the phloem cells function to distribute food materials. Xylem cells.

Primary dicotyledonous plants form a network that is centered in the middle and amounts to 2-4. While the primary phloem cells are scattered in groups between the networks. In most dicots, the cells right in the middle will develop into xylem.

Primary Root Parts

1. Root Cap The root

cap is located at the tip of the root and protects the root promeristem and helps the penetration of soil by the root, consisting of living cells that often contain starch. The root cap develops continuously. The outermost cell dies, separates from the rest and disintegrates, then is replaced by new cells formed by budding.

2. Epidermis

The epidermal cells of the root are thin-walled and usually without a cuticle. However, sometimes the outermost cell wall is cuticle.
A characteristic feature of roots is the presence of root hairs which are adapted to absorb water and soil salts. Root hairs are epidermal cells that extend outward, perpendicular to the root surface, and are tubular.

3. Root cortex

In general, the cortex consists of parenchyma cells. In the large number of monocots that do not shed their cortex while the root is alive, a lot of sclerenchyma is formed. Cortical cells are usually large and have large vacuoles. The plastids in it collect starch. The innermost layer develops into the endodermis and one or more of the outermost layers of the cortex may develop into the exodermis.

4. Exoderm

In a large number of plants, the cell wall in the outermost cell layer of the cortex will form a cork, resulting in a new protective tissue, the exodermis, which will replace the epidermis. The structure and cytochemical properties of exodermal cells are similar to those of endodermal cells. The primary wall is covered by suberin and the layer is again covered by cellulose. Lignin can also be found. exodermal cells contain living protoplasts when mature.

5. Endodermis

In the area of ​​​​the root used for absorption, the cell wall of the endodermis contains a layer of suberin in its anticlinal walls, i.e. on the radial and transverse walls. The sheer thickness of the coating earned it the name ribbon and the name Caspary. The band is the union between the middle lamella and the primary wall, where suberin and lignin are stored. If the cell is plasmolyzed, the protoplast detaches from the wall but remains attached to the necessary band.

6. Vessel

Cylinders Cylindrical vessels consist of a network of vessels with one or more layers of cells on the outside, namely the pericycle. If the middle part is not occupied by vascular tissue, then that part is filled with pith parenchyma on the inside, the pericycle is directly adjacent to the protophloem and protoxylem. The pericycle can retain its meristematic properties in which lateral roots, phellogens, and part of the vascular cambium are formed.

4. Secondary root

Secondary roots are roots that grow from other roots or can be called branch roots. Secondary growth is typical for the roots of dicot plants. Secondary growth is found in typical roots of Gymnosperms and Dicotyledoneae. Monocotyledoneae roots usually do not undergo secondary growth.

Secondary root structure

When secondary growth begins, cambium first appears in the parenchyma between the primary xylem network and in the primary phloem. Cambium will form secondary xylem and secondary phloem out. Then, the cambium is expanded laterally due to the differentiation of the initial cambium in the pericycle around the ends of the xylem network and also begins to form secondary weaves. Then the cambium forms a circular area in which there is secondary xylem that completely covers the primary xylem. The primary phloem and endodermis are usually destroyed by the stresses of the weave that grows within them.

Initially, the vascular cambium is band-shaped, the number of which depends on the type of root. In a diarch root, there are two bands, in a triarch root there are three band roots, and so on. Pericycle cells located outside the xylem area also become active like the cambium. Next, the cambium completes the circle with the xylem as the center.

The cross-section of the cambium in early development is oval, in diarch roots, triangular in triarch roots, and polyarchs in polymathic roots. The cambium is adjacent to the inner surface of the phloem which functions to form secondary xylem towards the inside and secondary phloem to the outside. The cambium produces xylem and phloem by dividing perinkin and anticline so that the root circle increases. Periderm formation follows the growth of secondary vessels.

Pericycle cells continue to divide periodically and anticline. Perinclinic cleavage causes an increase in the number of pericycle layers. The increase in the thickness of the vascular network and the pericycle pushes the cortex outwards, causing the cortex to rupture. Felogen outside the pericycle will form felem outward and phelloderm inward. In the roots of perennial plants, the activity of the vascular cambium and phellogens continues throughout the year. The development of roots, as in the case of stems, will also form a rhythm.

In dicotyledonous plants, for example in Medicago sativa, the secondary xylem consists of vessels with thickened walls that ascend the ladder and mesh. These vessels also contain fibers and parenchyma cells. Phloem contains vessels with companion cells, fibers, and parenchymal cells. Phloem on the outside contains only fibers and parenchyma; old vessels will be damaged. The phloem will merge with the parenchyma in the periderm unless there are fibers. Cork is a felogen derivative that functions as a protective tissue. Secondary growth in different Dicotyledonous plants perceive differently.

In woody plant roots, the vascular tissue usually has many cells with secondary walls containing lignin. Gymnosperm roots have the same type of secondary plant as the roots of Dicotyledoneae plants. However, there are histological differences between roots and stems. In roots, the proportion of elements with lignin secondary walls is smaller than in wood and bark, but the proportion of parenchyma tissue is greater. Research on Plantanus wood shows that wood and roots are phylogenetically more primitive than stems.

Secondary Root Parts

Formation of secondary vascular tissue by cambium
The initial development of vascular cambium is by division of procambial cells between primary phloem and undifferentiated primary xylem. This cylindrical cambium with a wavy outer edge has different activities; inside the phloem, the cambium produces xylem more quickly than elsewhere. In that place, the cambium is pushed out more quickly and finally a cylinder with a flat edge is obtained.

The cambium will form xylem cells inward and phloem cells outward, but in general the frequency of xylem formation is greater than that of phloem cells. This causes the secondary xylem to be thicker than the secondary phloem. Periderm formation by phellogen vessels and usually begins to form first in the pericycle. In perennial plants, root cambium activity will be accompanied by peridem activity for a long time. Periderm that has been formed will not last long because the volume of new cells that are on the inside is getting bigger, and finally a new periderm is formed underneath. This can take place repeatedly until a rhythm is obtained.

Root Characteristics

1. Root is one part of the plant that is usually in the soil, root growth leads to the soil.
2. In general, roots stay away from light so that their growth will be faster.
3. Roots are not like other plant parts such as stems and leaves which have a green color because the leaves contain chlorophyll, the color of the roots is whitish or yellowish.
4. Its growth occurs at the tip of the root which is one of the primary growth points where there is a meristematic tissue, as well as the apical dominance mechanism that occurs in a root.
5. At the tip of the root has a tapered shape and serves to penetrate the soil and can break rocks.

Water and Mineral Absorption Process

Water and minerals are absorbed by the root tips and root hairs (by osmosis) into the plant body. Osmosis is the movement of substances from a solution of low concentration (less concentrated) to a solution of high concentration (more concentrated) through a semipermeable membrane. A semipermeable membrane is a separating membrane that only water and certain substances can pass through. But apart from osmosis, absorption of water and minerals can be carried out by active transport, that is, the system of transporting ions and molecules through cell membranes using energy.

Then, from the root hairs, water and minerals flow in a horizontal direction through the epidermis, cortex and endodermis to the xylem. From the xylem, water and minerals are transported to the leaves through the woody vessels (xylem) in the stems, branches, and leaves as photosynthetic materials. This transport is called vascular transport.

Then, water entering the plant cell causes turgor. What is turgor? Turgor is a state of tension between the cell wall and the contents of the cell after absorbing water.

Roots as a Respiratory Tool in Plants

The root is also used as a breathing apparatus called the root of the breath. Breath roots are found in plants in mangrove forests, which grow upright at the base of their stems. At the root of the breath, there are many openings for air to enter.

However, apart from having breath roots, there are also hanging roots. Hanging roots grow from the above-ground part of the stem towards the ground. The function of the hanging roots while still hanging is to absorb air. But when the root part that goes into the soil, the root part has a function like ordinary roots, namely, absorbing water and minerals. Then, the oxygen absorbed by the roots is used for the process of absorption of water and minerals.