Pneumatophores are spongy erect roots extending above the surface of the water that facilitate the exchange of oxygen and carbon dioxide for the roots.
Produced by a plant growing in water, pneumatophores are specialized root structures (above-ground spongy outgrowths of roots) that grow out from the water surface where inadequate oxygen required for normal respiration of the roots is present.
A large number of breathing pores for the exchange of gases facilitate the aeration necessary for root respiration.
Some examples can be seen in many mangrove species like Avicennia germinans, Laguncularia racemosa and Ludwigia repens.