Intercalary Meristem

A plant’s structural framework consists of different types of tissues. 

Plant tissues are divided into two main types based on their capacity. One of these two types is permanent tissues and the other is meristematic tissues. The meristematic tissues cells never lose their capacity to divide. But this is not the case for permanent tissues. Meristematic tissues never differentiate to gain permanent size, shape, or function. Instead, these issues are comparatively immature, small and have a high respiration rate, and are cytoplasmically dense.

Meristematic tissues are divided into two types, one is primary and the other is secondary meristems. From the meristems of embryos, the primary meristematic tissues are directly derived. On the other hand, from the permanent tissues, secondary meristematic tissues are derived by following the process of dedifferentiation. Primary meristematic tissue is of three types based on the tissue position. These three types are:

• Apical meristem
• Intercalary Meristem, and
• Lateral Meristem

Apical meristem helps grow a plant at the apices (both shoot and root apices). Intercalary meristem helps in growing the plant body. Lateral meristem helps the girth of the plant body.

Definition of Intercalary Meristem

Intercalary Meristem is a permanent meristematic tissue that helps a tree or a plant grow vertically with its length. The meristematic region cells are totipotent, small, full of protoplasm, and thin-walled.

Intercalary Meristem has the following features:

• Primary (originates directly from an embryo) by the origin.
• Dividing in nature.
• Intercalary (between permanent tissues) by position.

Intercalary Meristem is active and helps in the intercalary or vertical growth of the plant. But intercalary meristem has a limit and it’s not like the other meristematic primary tissues. Eventually, it will reach a limit and gradually mature into permanent tissues. 

Sources of Intercalary Meristem

Mainly from two sources, intercalary meristem can arise. These two sources are far from the root and shoot tips. Among them, one source is subapical meristem. This meristem lies at the apical meristem base and directly contributes to the formation of the intercalary meristem. Another source is the dedifferentiation process of the mature tissue, which indirectly leads to intercalary meristem forming in the plant’s later stages of life.

What is Subapical Meristem?

Subapical Meristem happens with division activity of gradual restriction to any region of the floral/internode spike, in which it is prolonged enough to significantly contribute to the internodal tissues.

What is the dedifferentiation of mature tissues?

Intercalary meristem usually develops into matured tissues. But even after maturation, some of its parts remain ‘silently preserved’. In the time of some development, growth, or environmental triggering conditions this tissue goes into dedifferentiation. The mature tissue dedifferentiation means cell transformation from a highly differentiated stem to a less differentiated one.

What does Intercalary Meristem look like?

Intercalary meristem is a kind of meristem tissue associated with the length growth of a plant in the middle position. It is made up of meristematic cells and mitotically divides the stem based on the leaf blades and nodes. At this point, the growth of a plant is known as intercalary growth. The main function of intercalary meristem is to provide growth and elongation of the part of the plant. They are capable of cell division, allow rapid growth of the plant, and help in the regrowth of many monocots.

Functions of Intercalary Meristem

A plant organ or tissue just like the animals can perform various roles in different genera, lineages, and species. Similarly, the tissue of the intercalary meristem also plays different actions. Starting from vertical growth of grazing tolerance to the formation of gynophores, it serves all the requirements of plants for survival. The few most important roles of intercalary meristem are the following:

• Intercalary meristem helps the cereal plants of fallen stems to become erect.
• To regenerate lawn grass that is removed by repeated mowing or grazing herbivores intercalary meristem is helpful.
• Intercalary meristem helps to grow bamboo by elongating the internodes.
• In the case of the development of physiology and morphology of grasses, it is very helpful. As the grasses grow, whole-leaf primordium becomes involved in meristematic activity, gradually turning into cellular division. But eventually, this cellular division is restricted to intercalary meristem. In the time of ligule formation, intercalary meristem exists within the blade, and in the time of exposure, intercalary meristem tissue exists within the sheath.

Conclusion

On a final note, we can say that intercalary meristem helps a tree or a plant to grow vertically with its length. The meristematic region cells are totipotent, small, full of protoplasm, and thin-walled. The most important feature of intercalary meristem is that starting from vertical growth of grazing tolerance to the formation of gynophores, it serves all the requirements of plants for survival. Intercalary meristem can arise from two sources. These two sources are very far behind the root and shoot tips. Among them, one source is subapical meristem. This meristem lies at the apical meristem base and directly contributes to the formation of the intercalary meristem. Another source is the dedifferentiation process of the mature tissue, which indirectly leads to intercalary meristem formation in the plant’s later part of life. It also helps to grow bamboo by elongating the internodes.