What is the difference between apical meristem and lateral meristem?

Introduction

The Meristem is a different type of tissue that is located in areas of plants where growth is going to take place. The word Meristem is derived from the Greek word “merizen” which means ‘to divide’ and the word meristem was first coined by Karl Wilhelm von Nageli. Meristem is the tissue in plants that contains undifferentiated cells, also known as meristematci cells. There are two types of meristematic tissues, namely primary meristem and secondary meristem.

Differences in structure and location

Primary or apical meristem is the tissue from which the main stem of a plant arises while lateral meristem is the one from which the plant grows laterally. The apical meristem is also called as the growing tip and it is found in growing buds and growing roots. Lateral meristems are placed in such a way that they surround the apical meristem and hence always cause growth laterally. Lateral meristem helps the plants to increase in width and increase their diameter. Apical meristems are very small as compared to the larger lateral meristem. Apical meristems are responsible for the primary growth of the stems and roots of the plants and hence they will help increase length and height of the plant.

Primary meristems have many cells where there is constant growth taking place. Most of the cells undergo mitosis in the apical meristem. Cells placed in the apical meristem are box like in appearance.

Apical meristem usually differentiates into three kinds of meristems. Lateral meristem differentiates into 2 types of tissues namely vascular and cork cambiums. Likewise, the apical meristem is divided into protoderm, procambium and ground meristem and it is responsible for the lengthwise growth of the plants.

Differences in function

The main function of the apical meristem is to initiate the growth of new cells in the seedlings of the tips of the root and shoots. The lateral meristems are equally important as they are responsible for radical growth of the plants and initiate growth where the apical meristem ceases to initiate growth. Vascular cambium produces woody growth in plants and maintains this continuous process which goes on for life. The apical meristem helps the plant grow deeper roots and give strong support to the plants.

There are many plants which do not undergo secondary growth due to the absence of lateral meristems and are called herbaceous plants while the ones which undergo woody growth are called as arboraceous plants.

Summary:

There are numerous differences between the apical and lateral meristem. Let us summarize the differences, the most important being the function of the apical meristem being growth in length and the function of the lateral being increase in girth of the stem and the plant. The apical meristem is placed at the apex and the tip of the roots so that it causes increase in height of the plant due to multiplication of the cells and the lateral meristem is placed surrounding the apical meristem and it initiates growth once the apical meristem stops functioning. Apical meristem is much smaller in size whereas the lateral meristem is much larger in size.

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