Apical Meristem Definition

The apical meristem is the growing tip of a plant, and is undifferentiated meristematic tissue located at the growing shoot tips and buds of plant roots. The main function of the apical meristem is to start the growth of new cells at the shoot and root tips of plants. Compared to the more cylindrical shaped lateral meristems, apical meristems are smaller.

The apical meristem is composed of several layers;  the number of layers depends on  plant type.

Tunica is the outermost layer and the innermost layer is called the corpus.

The tunica of monocots determines the physical characteristics of the leaf margin and edges; while the layer of corpus can distinguish the leaf edge’s characteristics in dicots.

Both of the tunica and corpus play a major role in the physical appearance of plants because every single plant cell is formed from the meristem.

Location of Apical Meristems

The apical meristems are primarily located in two locations, the stem and the roots.

Although there are some arctic plants that have apical meristems on the middle or lower part of the plant, such meristems only evolved due to the fact that they are advantageous in certain Arctic conditions.

There are two major types of apical meristems: the shoot apical meristem and the root apical meristem.

Apical Meristem Function

The cells found at the shoot apical meristems (SAM) serves as the surrounding peripheral region’s stem cell, wherein they rapidly proliferate and will be turned into flower primordial or differentiating leaf. This is basically the site where the embryogenesis in flowering plants takes place. The primordial of petals, sepals, leaves; ovaries and stamens are initiated in this location at the rate of one in every time interval, known as plastochron. Information on meristem identity genes.

The root apical meristems produce cells in two different dimensions;  they are covered by the root cap to serve as a protection against pathogens, dirt and rocks. A quiescent center is found at the center of the root apical meristem that has a low mitotic activity. The new formed cells in this region are established in the embryo of the primary root that will give rise to secondary roots.

©2005-2015 Plant Biology Advice - Dean Ravenscroft