The specialized aerial roots that stem out from a subterranean root system and enable plants to utilize the air in waterlogged soil habitats are called Pneumatophores. It is commonly found in mangrove species, bald cypresses, gyms, etc that grow in saline mudflats. It is also known as breathing roots in mangroves. They are lateral roots and grow outward out of the mud and water and function as a site of intake of oxygen for the primary root system inside the water. They have openings called lenticels in their bark which is small in size. They are also known as the respiratory or knee roots and are a characteristic of many species.
Pneumatophores in Trees
Hydrophytic trees have several modifications for their survival and growth in muddy and aqueous environments. Some species of trees like bald cypresses, gum produce a large number of lenticels on their bark that facilitate air exchange. Others exhibit a greater exchange of oxygen through the bark of the tree and into the tissue layer called cambium at lower oxygen concentrations. Hydrophytic trees generally have large intercellular spaces in their tissues to promote aeration of their roots. Hydrophytic species are adapted to anaerobic metabolism and can withstand the toxic by-products of this process such as ethyl alcohol and lactic acid. Some trees in the Amazon survive several months of being submerged in water each year.
Pneumatophores in Mangroves
Pneumatophores or respiratory roots are a characteristic of mangroves (like Avicennia germinans and Laguncularia Racemosa), plants that grow on muddy coasts and in salt marshes. Some roots become specialized as pneumatophores. Pneumatophores undergo negative geotropism and grow upwards. The roots come out of the mud and have small openings called lenticels that take in the air and pass it through the tissues to the roots beneath the water. The roots grow up to some centimeters above the low-tide level. Stilt roots are present in red mangroves that function in aeration as well as the support of the plant.
Necessity of Pneumatophore Roots in Mangroves
For respiration, every plant needs oxygen from the soil. In coastal areas, the soil is often washed by salty seawater during high tide and becomes salt marshes. That is why the oxygen quantity of the soil in salt marshes is very limited. Pneumatophores are breathing roots with numerous pores open in the air. As an adoption property, the mangrove plants have pneumatophores for this function. The plants can absorb oxygen from the air through their pneumatophores. Thus, the oxygen absorbed by the pneumatophores helps in the respiratory system and also enters the underground tissues for their growth. Also, pneumatophores help mangrove plants to absorb gases like nitrogen and essential nutrients like iron from the poor soil. Mangrove plants store the gases inside the pneumatophores so that they can use them even when the plants are submerged into water.
Functions of Pneumatophores
Pneumatophores are lateral roots that extend out of the surface of the water and facilitate the exchange of oxygen and carbon dioxide for the roots submerged in water. They are specialized aerial root structures present in plants where the oxygen required for normal respiration of roots is inadequate. A large number of breathing pores or openings called lenticels are present for the exchange of gas making the aeration process possible for root respiration. The roots are a modification for making the respiration of roots possible. These types of roots are found mainly in swampy and muddy areas and are a characteristic of many mangrove species like Avicennia germinans, Laguncularia racemosa, and Ludwigia reopen.
1. What is Pneumatophore?
Solution: Pneumatophore is a special type of breathing root, which is stemmed out from the subterranean root system. It helps the plants of salt marshes to absorb oxygen and other gases from the air.
2. in Which Area, Pneumatophores are Found?
Solution: Usually, pneumatophores are found in mangrove forests. Mangrove forests are located in the river bank areas and coastal areas, where the rivers meet the sea. The soil of the mangrove forests is often washed with seawater and the forest becomes salt marshes.
3. Give One Example of the Mangrove Plant, Which Has Pneumatophores.
Solution: Heritiera fomes is a tree of the mangrove forest, which has pneumatophores.
4. What is the Functional Organ of Pneumatophores, Which Helps in Breathing?
Solution: Pneumatophores have open pores in the air called lenticels. These lenticels help in absorbing oxygen and other essential gaseous exchange.