Question

Why are underground stem swollen?​

Answer 1

Iris. Stolon - Horizontal stems that run at or just below the soil surface with nodes that root and long internodes, the ends produce new plants. When above ground they are called "runners". Tuber - An enlarged fleshy end of a stem, generally from rhizomes but often also referring to thickened roots too.

Underground stems are modified plants that derive from stem tissue but exist under the soil surface. They function as storage tissues for food and nutrients, propagation of new clones, and perennation (survival from one growing season to the next).

Answer 2

Horizontal stems that run at or just below the soil surface with nodes that root and long internodes, the ends produce new plants. When above ground they are called "runners". Tuber - An enlarged fleshy end of a stem, generally from rhizomes but often also referring to thickened roots too.