Next, tubers are swollen tips of stems. Also, corms are the enlarged bases of the stem. With these given characteristics as well as preconceived notions one may hold, one may think that roots can only grow underground. This statement is far from the truth. In fact, some plants live only in water.
Plants living in water have special porous passageways that supply the roots with air.
Other plants that grow outside of the soil are ones containing parasitic roots. These grow high in the air and live off the sap streams of other plants. Yet other roots live and multiply without having any true roots. Plant propagation can fall into two categories, sexual and asexual propagation. Sexual propagation is usually performed through seeds, and it involves two individuals, usually a male and a female.