While the main functions of roots are to anchor the plant and to take up water and nutrients, some roots may serve other purposes in certain environments. Many epiphytes in tropical rainforests have highly modified roots that allow the plants to survive high in the rainforest canopy where water and nutrients are not so readily available.

      Myrmecodia species have swollen hypocotyl regions covered with thorn roots. The swollen region contains chambers where ants live. The ants provide the plant with nutrients when the ants die and decay inside the plant, and the plant produces the thorn roots that prevent ant-eating predators from disturbing the ant's home.

      Roots may also serve as storage areas for nutrients and/or water. In radishes the hypocotyl region begins to expand as photosynthates, usually carbohydrates begin to accumulate. Eventually these reserves accumulate downward into the taproot. In Pachypodium this storage works in reverse: the root begins to swell with water and eventually water storage moves up into the hypocotyl region. Other examples of storage roots include beets, rutabagas, and carrots.

      Contractile roots are another type of root specialization. A contractile root can pull the shoot apical meristem below ground surface for overwintering. Some spring bulbs such as crocus undergo contraction against full soil resistance. As the root contracts, it pulls the bulb down into the soil and compacts the soil located under the bulb. Some plants, like the dandelion, move without soil resistance. In this case, the root grows downward initially via cell elongation, then the cells expand laterally resulting in contraction of the root. There is no compaction of the soil and a channel is left behind the contracted root. The contracted portions of the roots on a dandelion plant make it virtually impossible to pull up a dandelion plant with the roots intact.

      Stilt roots, such as those found on red mangrove (Rhisophora), allow these plants to live in a habitat that experiences frequent flooding. Since the substrate is often under the surface of the water, stem-borne stilt roots form a tripod-like support for the shoot system. Stilt roots are commonly found on plants with an obconate shoot form.

      Some Ficus species have prop roots that originate from the lower surface of lateral branches. These prop roots support the lateral branches as they extend great distances from the main trunk of the tree.

      Pneumatophores are specialized roots produced by some trees (e.g. Taxodium, bald cypress, Avicennia, black mangrove) adapted to life in swamps. Pneumatophores grow upward (i.e. they are negatively geotropic) into the air above the anaerobic muck in which the rest of the root system is found. The surface of the woody pneumatophore is covered with lenticels that allow air to diffuse into the rest of the root system.

      Aerial roots serve several purposes to epiphytic plants. Many orchids have aerial roots covered with velamen, multiple layers of dead epidermal cells that absorb water and nutrients directly form the air. The aerial roots of some epiphytic orchids have a cortex containing chloroplasts for photosynthesis. These aerial roots may be tendril-like and twine to hold the plant to its substrate. These roots show a thigmotropic response and twine around various objects.