In parts of the South new sweet potato plants are obtained by cutting
parts of the stems from growing plants and planting them.

Florists produce large numbers of new plants by taking advantage of
this function of stems.

=Experiment.=--Take a white potato which is a thickened stem and place
it in a warm, dark place. It will soon begin to sprout or send out new
stems, and as these new stems grow the potato shrinks and shrivels up.
Why is this? It is because the starch and other material stored in the
potato are being used to feed the new branches. When we plant potatoes
in the garden and field the new plants produced from the eyes of the
potato are fed by the stored material until they strike root and are
able to take care of themselves.

All stems store food for the future use of the plant.

Annual plants, or those which live but one year, store food in their
stems and leaves during the early part of their growth. During the
fruiting or seed forming season this food material is transferred to
the seeds and there stored, and the stems become woody. This is a fact
to bear in mind in connection with the harvesting of hay or other
fodder crops. If we let the grass stand until the seeds form in the
head, the stem and leaves send their nourishment to the seeds and
become woody and of less value than if cut before the seeds are fully
formed.

In plants of more than one year's growth the stored food is used to
give the plant a start the following season, or for seed production.