Tubers

Tubers are ‘taters, but there’s more to them than that.

Tubers are modified underground stems (geophytes) that store water, sugar, and other nutrients, to get plants through winter and drought, to help them start back up in spring, and to regenerate themselves, asexually. Some people say that underground runners (stolons) are also tubers, but not everyone agrees.

Young potato plant with baby tubers

Stem tubers

Potatoes and yams are stem tubers. These structures are modified stems from thickened stolons (runners) or rhizomes (underground stems). The ‘eyes’ you see on a potato are buds. New plants can grow from these buds, as well as from the distal (far) end of the tuber.

Root tubers

Root tubers, or tuberous roots, on the other hand, are modified lateral roots which store nutrients and sugars in the same way as stem tubers. Sweet potatoes, dahlias, and cassava (tapioca) are examples of root tubers. These tubers do not have ‘eyes’ that can generate new plants. Instead, growth occurs at the far (distal) end, as well as from the crown area where foliage is already growing. Tuberous roots are biennial:

1. The first year, root tubers are generated.
2. At the end of the growing season, the above ground portion of the plant dies.
3. In spring, the root tubers generate new plants before shriveling up and disappearing.

What sort of tubers are you growing?