Question

The main function of lenticels is
A. Transpiration
B. Guttation
C. Bleeding
D. Gaseous exchange

Answer 1

Lenticels are the raised structures that are porous. These pores are situated over the epidermis of leaves, woody plants, or bark of woody stems. The presence of lenticels is used for the identification of trees. Carbon dioxide and water vapor exchange take place through lenticels.

Complete answer: Lenticels are tissues present in the periderm of secondary thickened organs. It is a porous tissue having large cells with intercellular spaces that allows gaseous exchange through the organs of the plant, bark of woody stems, and roots of dicotyledonous plants. These are raised porous structures that provide a pathway for the direct gaseous exchange. It helps in the exchange of carbon dioxide and water vapor between internal tissues and the atmosphere. As the bark is impermeable to gases, these are mainly found over the bark of the trees. The extinct species of arboreal plants of genera Sigillaria were reported to be the first plant species to have lenticel tissue. The lenticels form beneath the stomatal complexes during the primary growth period of the periderm. The lenticel formation is related to the strength and growth of the shoots of the plants. On maturation of roots, the lenticels continue to develop in the new periderm. These can be characterized by circular, oval, or elongated areas on the stems. The lenticels appear rough, cork-like structures on woody plants. Under the lenticels layers, the porous tissues create several spaces between the cells. In mangoes, discoloration of lenticels can be seen due to lignin that is present in cell walls. Transpiration is the process of evaporation of water vapor from the leaf surface due to the opening and closing of stomata. Guttation refers to the secretion of droplets of water oozing out of pores present in plants. Guttation happens because of pressure created inside the plant due to the absorption of water by roots. On the other hand, bleeding is a process through which the plant loses its content from the site of the wound.
Therefore, the right answer is option D.

Note: The common Mangrove species live in oxygen-deprived conditions. This makes respiration a challenge. Thus, these plants possess specialized structures having lenticels. These appear on pneumatophores. Also, in grapes on the pedicles, lenticels can be found. Many fruits also contain lenticels like apples.