Root Apex : (a) It is found at the tip of main root and its branches.
(b) It is derived from radicle part of the embryo and its derivatives, in case of tap root system.
(c) In adventitious roots, it is produced from the derivatives of shoot apex.
(d) The root apex is sub-terminal because it is covered by the root cap.
(e) The root apical meristem (root apex) gives rise to three meristematic regions : (i) Protoderm, (ii) Procambium, (iii) Ground meristem.
(f) Protoderm form epiblema and root cap (calyptra).
(g) However, in monocots, the root cap is derived from a special meristematic region at the end of the root called calyptrogen.
(h) The cells of the root cap secrete a mucilaginous substance that acts as a lubricant.
(i) The root cap cells are parenchymatous and short-lived.
(j) They contain starch grains.
(k) Procambium produces vascular tissues. Ground meristem forms pith, endodermis and cortex.
(l) In many cases, a small region with very low mitotic
activity is present in the centre of the root apex. It is called quiescent centre.