<P> Tubers are enlarged structures in some plant species used as storage organs for nutrients . They are used for the plant's perennation (survival of the winter or dry months), to provide energy and nutrients for regrowth during the next growing season, and as a means of asexual reproduction . Stem tubers form from thickened rhizomes (underground stems) or stolons (horizontal connections between organisms). Common plant species with stem tubers include potato and yam . Some sources also treat modified lateral roots (root tubers) under the definition; these are encountered in sweet potato, cassava, and dahlia . </P> <P> The term originates from Latin tuber, meaning "lump, bump, swelling". </P> <P> Some sources define the term "tuber" to mean only structures derived from stems; others use the term for structures derived from stems or roots . </P>

How do sweet potatoes reproduce through their roots