<P> The tuber has all the parts of a normal stem, including nodes and internodes . The nodes are the eyes and each has a leaf scar . The nodes or eyes are arranged around the tuber in a spiral fashion beginning on the end opposite the attachment point to the stolon . The terminal bud is produced at the farthest point away from the stolon attachment and tubers thus show the same apical dominance as a normal stem . Internally, a tuber is filled with starch stored in enlarged parenchyma like cells . The inside of a tuber has the typical cell structures of any stem, including a pith, vascular zones, and a cortex . </P> <P> The tuber is produced in one growing season and used to perennate the plant and as a means of propagation . When fall comes, the above - ground structure of the plant dies, but the tubers survive over winter underground until spring, when they regenerate new shoots that use the stored food in the tuber to grow . As the main shoot develops from the tuber, the base of the shoot close to the tuber produces adventitious roots and lateral buds on the shoot . The shoot also produces stolons that are long etiolated stems . The stolon elongates during long days with the presence of high auxins levels that prevent root growth off of the stolon . Before new tuber formation begins, the stolon must be a certain age . The enzyme lipoxygenase makes a hormone, jasmonic acid, which is involved in the control of potato tuber development . </P> <P> The stolons are easily recognized when potato plants are grown from seeds . As the plants grow, stolons are produced around the soil surface from the nodes . The tubers form close to the soil surface and sometimes even on top of the ground . When potatoes are cultivated, the tubers are cut into pieces and planted much deeper into the soil . Planting the pieces deeper creates more area for the plants to generate the tubers and their size increases . The pieces sprout shoots that grow to the surface . These shoots are rhizome - like and generate short stolons from the nodes while in the ground . When the shoots reach the soil surface, they produce roots and shoots that grow into the green plant . </P> <P> A tuberous root or storage root, is a modified lateral root, enlarged to function as a storage organ . The enlarged area of the root - tuber, or storage root, can be produced at the end or middle of a root or involve the entire root . It is thus different in origin but similar in function and appearance to a stem tuber . Examples of plants with notable tuberous roots include the sweet potato, cassava, and dahlia . </P>

The edible portion of an irish potato is a