The stem of some plants has evolved undergoing profound transformations that have made it suitable for performing completely particular functions. There are various types of transformed stems that we can easily observe in nature: rhizomes, tubers, bulbs, tuber bulbs, stolons, cladodes, columnar stems, tendrils, thorns ... The functions performed are different, in some cases they are intended organs the accumulation of reserve substances, often however also capable of surviving in the soil during the winter to develop in plant the following spring; in other cases these are support organs (tendrils) or defense organs (thorns) or organs suitable for rapid vegetative reproduction (strawberry stolons).
Stem adaptations (source Iprase Trentino)
Rhizomes and stolons
The stem, to adapt to particular environmental problems, can present significant modifications. The transformed drums have specific shape and characteristics. The stolone is a modified stem that can be observed in the strawberry, it separates from the mother plant and crawls on the ground and gives rise to a new seedling. The rhizome is an underground stem that resembles a root, but has leaves, buds and adventitious roots (it is the typical stem of the bermuda grass).
Tuber and bulb-tuber
Tuber and bulb-tuber are other types of transformed stem. The potato is the most common example of tuber, it is located on the same level as the roots. The tuber, like the other stems, has numerous buds (eyes), has a reserve function and plays an important role in vegetative propagation (asexual reproduction without the need for flowers and gametes). The bulb-tuber is typical of the tulip and gladiolus, it lacks the leaves and is compact and fleshy.
Strawberry Stolone - Potato Tubers (drawing by Daniela Baldoni)