Question

Write a note an sub aerial modifications of the stem.

Answer 1

Subaerial Modifications: The stem of some plants remains sub- aerial which grows horizontally on the surface of the soil for the purpose of reproduction. There are four types.

1. Runner: The stem grows laterally on the surface of the soil, breaks up to produce roots where it touches the ground to give rise to new plants. Eg: Centelk (Vallarai).
2. Stolon: A Stolon is a slender branch of the stem that grows upwards to some distance and then bends towards the ground. Upon touching the ground, it gives rise to a new plant. Eg. Wild strawberry.
3. Sucker: is a short and weak lateral branch that grows diagonally upwards and directly gives rise to a new shoot. Eg. Chrysanthemum.
4. Offset: An offset is a short and thick branch that arises from the axial part of a leaf. It has thick internodes. It produces a tuft of leaves and a cluster of small roots below. Eg: Eichhornia.