Question

What are pneumatophores?

Answer 1

In plants, roots are the underground part that shows different types of modifications. But in some cases, roots are grown out above the soil surface for respiration. This happens in the swampy areas where roots are not able to respire underground.

Complete answer:
Pneumatophores are the modification of roots in the mangrove plants that helps in the gaseous exchange. These are also known as breathing roots that grow aerially. It is found in swampy areas like near seashores. In pneumatophores, the secondary and tertiary roots come out from soil for the respiration process or exchange of gases by their lenticels or pneumatophores which are present near the tip of the root. The surface of the root without lenticels is covered with cork and the remaining root inside the soil consists of absorbing roots. It is found in mangrove plants like Rhizophora , Sonnerita , Avicennia , Heritiera etc.

Additional Information:
Other root modifications are fleshy tap or adventitious roots, nodulated tap or adventitious roots, additional support and other vital functions. The vital functions of roots include assimilatory or photosynthetic roots which perform photosynthesis, parasitic roots which absorb nourishment from the host, hygroscopic or epiphytic roots which grow as epiphytes on trunk or branches of the tree, floating roots which is buoyant and arise at the nodes, reproductive roots which reproduce new plants under favourable condition, contractile roots shrink more than original length, leaf roots are modified leaves and root thorns are replaced adventitious roots which get modified into hard, thick and pointed thorns.

Note:
Some plants are rootless like submerged aquatic plants that do not have roots and they absorb water and minerals from the stem and leaves like in Ceratophyllum , Myriophyllum , etc. Some aquatic plants have roots only for balance and fixation.