Apical Meristem - Structure, Defination, Overview

There are three types of meristematic tissue that are present in plants, namely: apical meristem, intercalary meristem, and lateral meristem. Meristematic tissue is defined as the tissue that helps the cells grow and divide and performs many different functions. The apical meristem is defined as the growth region in plants. It is present within the root tips and also in the tips of the new shoots and leaves. The apical meristem is one of three types of tissue. This tissue possesses the ability to differentiate into different cell types. A meristem is defined as the tissue due to which growth occurs in plants. Apical is defined as a growth that takes place at the tips of the plant, both top and bottom. The intercalary meristem is located between branches. Lateral meristems are meristems that grow in girth, such as in woody plants.

Importance of the Apical Meristem

The apical meristem is important as it provides access to both nutrients and water with the help of the roots. It also provides access to light energy through the leaves. Plants should grow in size by expanding in both directions of water and light. Some plants show the feature of apical dominance. This characteristic is defined as a region with only one main shoot apical meristem and the rest are accessory. In plants that possess apical dominance, there is a single main trunk that grows to great heights. If the apical meristem is cut down, the branches below this region will start to take on the role of the primary apical meristem. This will lead to the establishment of a bushier plant. Horticulturists make use of this phenomenon to increase their business yield and the yield of many different agricultural crops and ornamental plants.

Types of Apical Meristem

The apical meristem is usually present just below the surface of the branches and roots located away from the centre of the plant. The cells in both of these regions are continually dividing. Some cells divide into more meristematic cells and make secondary meristem tissue, and some other cells divide and differentiate into structural cells that attain a particular function and become permanent cells or vascular cells. There are two apical meristems based on location that are found in most plants.

The shoot apical meristem

This kind of meristem is present in the tips of plants. This apical meristem plays a role in creating new cells in the shoot region. It allows the growth of the stem to help the plant absorb light and air, where it can perform photosynthesis and exchange built-up gases.

The root apical meristem

This type of meristem is found at the tips of roots. By observing the conditions of the soil located around the root, signals are created with the help of the apical meristem, which leads to the movement of plants towards water and desired nutrients. It is due to this reason that roots are observed in pipes for water and drainage, which carry many of the nutrients they need. The apical meristem remains protected by the root cap and continues to secrete cells even when the root cap is carried away as it pushes through the dirt. The apical meristem should produce a sufficient number of cells to not only extend into the soil, but also to replace the cells lost due to abrasion.

Apical meristem structure

The apical meristem is present directly below the root cap in the root. The apical meristem is observed to be a group of densely packed, undifferentiated cells. Various cells will form from these cells, assisting in the formation of structures for the plant's use. An undifferentiated apical meristem cell will divide further and lead to the formation of a specialised cell.

When we observe the shoot apical meristem in most plants, it is capable of generating an entire plant, while the root apical meristem cannot. Scientists have made use of the ability of the shoot apical meristem to help clone many species of plant. This is done just by cutting off the apical meristem and then putting it in an appropriate growth medium. In this condition, the apical meristem will lead to the development of roots and differentiate into a whole new plant. There will be one more benefit: more apical meristems from the plant can be harvested for more clones. In this particular way, a desirable and important plant can be replicated almost indefinitely.

The shoot apical meristem is present particularly at the tips of plants when observed in many dicots, or it may generate slightly below the soil and synthesise leaves that grow upward, like most monocots. While the shoot apical meristem is defined as the growth centre of all above-ground growth in both groups.