Meristem: what is it, primary and secondary meristem, types

meristem is a plant tissue responsible for plant growth and by the formation of other types of plant tissue.

It consists of undifferentiated cells or that are in the embryonic stage.

These cells go through many cell divisions. In this way, they multiply, promoting plant growth.

During the cell division process, the initial cells remain undifferentiated in the meristem. while the derived cells they grow, go through new divisions and through the process of differentiation.

During differentiation, cells undergo chemical, physiological and morphological changes. Thus, the specialized cells that form the different tissues and structures originate.

Some cells (for example, parenchymal ones) maintain a lower degree of differentiation so that they can divide again and give rise to new cells.

This is particularly important for recovery from plant injuries.

Primary Meristem

The primary meristem is a type of meristematic tissue whose origin is embryonic. Its cells are present since the formation of the plant embryo, forming the primary tissues and all primary structure of the vegetable.

Apical meristem

The primary meristem is found at the apex of plant stems and roots, being called apical meristem or apical yolk.

The apical meristem is responsible for the plant's primary growth, that is, for the increase in the length of these organs.

With the formation of new cells, the older ones differentiate and incorporate into the meristematic tissues, which follow the apical meristem.

There are three types of primary meristematic tissues, they are:

  • Protoderm: it will differentiate into the epidermis, the plant's lining tissue;
  • Prochange: it will originate the primary xylem and phloem, tissues that form the vascular system;
  • Fundamental Meristem: will differentiate forming the fundamental tissues: parenchyma, colenchyma and sclerenchyma.

See too:

  • plant histology
  • Stalk
  • Parenchyma
  • Xylem and Phloem

Secondary Meristem

Secondary meristems originate from primary meristems, incorporating new cells into existing tissues. With this they help in the formation of the plant's secondary structure.

lateral meristem

You lateral meristems or side yolks they are found parallel to the longest axis of the plant and grow in that direction.

The lateral meristem is responsible for the secondary growth of the plant, which is the increase in width.

Secondary meristematic tissues are the cambium and phelogen.

the exchangeVascular differs in secondary xylem and phloem and the phelogen gives rise to the peridermis.

The peridermis is the lining tissue that replaces the epidermis. It will form the suber or cork (in the outermost part) and the pheloderm or secondary cortex.
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