Root and tuber crops are examples of specialized roots, while other specialized root types are aerial roots, parasitic roots, contractile roots and roots that can store food and water. Tuberous roots are enlarged roots that function as storage organs. Root tubers include sweet potatoes, carrots, parsnips, cassava and dahlia.
While common roots function as water-absorbing organs of a tree or a plant, specialized roots perform functions other than absorption and support. Aerial roots occur above the surface and enable climbing plants to attach themselves to trees, rocks, walls and other substrates. Parasitic roots, found in dodder and pinedrops, form peg-like projections that attach to the host's stem. Contractile roots that occur in bulbous plants shrivel in length and pull the plant deeper into the soil to protect the plant from the heat and sun during the dry season.