Meristematic tissue is growth tissue and the location of most cell division. It is known as undifferentiated tissue because cells in the meristematic tissue will eventually become vascular, ground, or dermal tissue.
Plants generally grow where meristematic tissue is present. At the tips of roots and stems, the meristematic tissue is called the apical meristem. The primary growth of the plant occurs in the apical meristem.
Lateral growth in a plant is called secondary growth; it occurs in lateral meristem tissue. Woody trees and shrubs display secondary growth when the plants become enlarged and thickened.