Question

If an apex of a plant is cut down it does not grow tall . Why?

Answer 1

Normally a plant has some meristematic tissue in its stalk/stem, and when the apexis cut off, the hormone that prevents all the non-apical-meristem from sprouting or growing is absent. When this happens all the dormant “buds” along the stem canbegin to grow.

Answer 2

at the tip or apex of root and shoot....

there is presence of meristematic tissues...
these tissues responsible for cell division , growth...

not other tissues have the capacity of cell division....

so that ...when we cut the shoot ....the meristems were cut off....and leads to .....stopage of growth ..