In the opposite direction, the roots receive sugars from the leaves through the phloem. The roots of many kinds of plants grow in symbiosis with one or another kind of fungus. The fungus absorbs dissolved minerals, particularly phosphorous, from the soil and passes them into the plant roots in return for sugars and other organic compounds. These mycorrhizal associations benefit both the plant and fungi. Some plants, particularly members of the legume family such as beans and clover, host bacteria in their roots.
Infected roots have characteristic round swellings called nodules.
Even though the bacteria consume a share of the plant's sugars, the plant benefits because these bacteria can gather nitrogen from the air and convert it into compounds that roots can absorb. Fibrous roots - Slender, mostly unbranched roots that look like fine string or yarn. Adventitious roots - Roots that grow from stems or leaves of a plant. Bulbs, rhizomes and corms are not roots but develop from leaves or stems and are considered storage organs. Stems Stems are the support structures of a plant.