Meristem is a group of plant cells that remain in a continuous state of division. It is a tissue system in plants called meristematic tissue. The term meristem was proposed by Karl Nägeli from a Greek word ‘merizein’ which means ‘to divide’. The meristem composed of rapidly dividing undifferentiated mass of cells. Meristems are usually found in the growing region of plant organs such as shoot apex and root apex. Usually meristem originates from the embryonic cells.
The primary function of meristem is to assist in plant growth and development. Meristematic cells are characteristically different from other differentiated cells in terms of many aspects. This post describes the characteristic features of meristematic cells in plants.
What are Characteristics of Meristems / Meristematic Tissues?
§. Meristem composed of rapidly dividing cells
§. Usually situated at the growing apex of plant parts (root apex or shoot apex)
§. Meristematic cells are undifferentiated
§. Size and shapes of meristematic cells varies
§. Cells more or less isodiametric in shape, sometimes circular
§. Intercellular space generally absent in meristematic tissue
§. Cell wall composed of primary cell wall only
§. Cell wall contains primary pit fields
§. Meristematic cells do not undergo secondary thickening
§. Cells contain dense granular cytoplasm
§. Vacuole usually absent, if present very small
§. Usually cells will be diploid
§. Cells do not store reserve food materials
§. Meristematic cells do not have ergastic substances
§. Endoplasmic reticulum will be very less in the cells
§. Internal structure of mitochondria are in less elaborative condition
§. Plastids present but they will be in the pro-plastid stage
§. Cells contain more number of ribosomes
§. Cells are metabolically very active
§. Meristematic cells are usually devoid of viral particles (hence meristem culture is used for obtaining virus free plant-lets)