Apical meristem
From Free net encyclopedia
The apical meristem, or growing tip, is a completely undifferentiated meristematic tissue found in the buds and growing tips of root in plants. Its main function is to begin growth of new cells in young seedlings at the tips of roots and shoots (forming buds, among other things). Specifically, an active apical meristem lays down a growing root or shoot behind itself, pushing itself forward. Apical meristems are very small, compared to the cylinder-shaped lateral meristems.
Apical meristems are composed of several layers. The number of layers varies according to plant type. In general the outermost layer is called the tunica while the innermost layers are the corpus. In monocots, the tunica determine the physical characteristics of the leaf edge and margin. In dicots, layer two of the corpus determine the characteristics of the edge of the leaf. The corpus and tunica play a critical part of the plant physical appearance as all plant cells are formed from the meristems. Apical meristems are found in two locations: the root and the stem.
Root Apical Meristems
The root apical meristem is covered by the root cap, which protects the apical meristem from the rocks, dirt and other pathogens.
Stem Apical Meristems
The stem apical meristem is multicellular and, unlike the root apical meristem has no cover.