Question

explain meristematic tissue in brief

Answer 1

A meristem is the tissue in most plants containing undifferentiated cells (meristematic cells), found in zones of the plant where growth can take place. Meristematic cells give rise to various organs of a plant and are responsible for growth.

Differentiated plant cells generally cannot divide or produce cells of a different type. Meristematic cells are incompletely or not at all differentiated, and are capable of continued cellular division. Therefore, cell division in the meristem is required to provide new cells for expansion and differentiation of tissues and initiation of new organs, providing the basic structure of the plant body. Furthermore, the cells are small and protoplasm fills the cell completely. The vacuolesare extremely small. The cytoplasm does not contain differentiated plastids (chloroplasts or chromoplasts), although they are present in rudimentary form (proplastids). Meristematic cells are packed closely together without intercellular cavities. The cell wall is a very thin primary cell wallas well as some are thick in some plants.[citation needed] Maintenance of the cells requires a balance between two antagonistic processes: organ initiation and stem cell population renewal.[citation needed]

There are three types of meristematic tissues: apical (at the tips), intercalary (in the middle) and lateral (at the sides). At the meristem summit, there is a small group of slowly dividing cells, which is commonly called the central zone. Cells of this zone have a stem cell function and are essential for meristem maintenance. The proliferation and growth rates at the meristem summit usually differ considerably from those at the periphery.

The term meristem was first used in 1858 by Carl Wilhelm von Nägeli (1817–1891) in his book Beiträge zur Wissenschaftlichen Botanik("Contributions to Scientific Botany").It is derived from the Greek word merizein (μερίζειν), meaning to divide, in recognition of its inherent function.

Answer 2

⇒ MERISTEMATIC (DIVIDING) TISSUE

These are living tissue which are capable of division throughout life.

  Characteristics →

• Thin Cell Wall

• Cell may be round , oval , polygonial or rectangular in shape

• Intercellular spaces are absent

• Large Nucleus and abundant Cytoplasm

• Contain undifferentiated cells

• Vacuoles are small or absent

TYPES OF MERISTEMATIC TISSUES :

⇒ APICAL MERISTEMATIC TISSUE

The apical meristem is the growth region in plants found within the root tips and the tips of the new shoots and leaves.

  Function → This apical meristem is responsible for creating cells and growth to drive the plant into the light and air, where it can photosynthesize and exchange built up gases.

⇒ INTERCALARY MERISTEMATIC TISSUE

  Location → They are present at the base of node and internodes.

  Function → Increase the length of plant as it brings about elongation of the internodal region.

⇒ LATERAL MERISTEM/SECONDARY MERISTEM

  Location → It occurs in lateral sides of the plant organ.

∴ In woody plants, secondary growth of stems and roots occurs through the activity of two lateral meristems: the vascular cambium and the cork cambium.

∴ Secondary growth occurs in all gymnosperms and most angiosperms, including most dicots but few monocots.

  Function → It increases the girth of plant.