Describe the sub-aerial modifications of the stem.
The primary function of sub-aerial stem modification is vegetative propagation. They are classified as follows: - a) Runners: - These stems are long and thin, with branches. They creep along with the ground and form roots at nodes. The mother plant produces a large number of such branches, which spread out in all directions. They may break off and start living as independent plants. Example: - Oxalis and doob grass. b) Stolon: - Stolon is a thin lateral branch that emerges from the base of the stem. It grows upward and then bends down, developing roots at the tip and producing a bud. The bud develops into a new plant. Example: - Mint and strawberry. ) Offset: - Offset is a thickened horizontal branch that emerges from the axil of a lower leaf. It is a short branch with a cluster of leaves above and tufts of roots below. The offset can detach from the mother plant and begin living on its own. Example: - water hyacinth and Water lettuce. d) Sucker: - The sucker is a lateral branch that grows from the underground portion of the stem. It grows obliquely upward and directly produces new plants. Example: - Banana and pineapple.
