What is plant coleoptile? Why does the removal of the coleoptile extremity disallow plant growth?
Coleoptile is first (one or more) aerial structure of the sprouting plant that emerges from the seed. It encircles the young stem and the first leaves, protecting them.
The top of coleoptile in general is the region where auxins are made. If this region is removed, plant growth stops since auxins are necessary to promote growth and tissue differentiation.