Question

What are lenticels? Mention their functions.

Answer 1

Hint: Plants develop different mechanisms to perform respiration. They may develop structures which facilitate the process. This is done to better the survival. They are adaptations. Lenticels are such structures. Lenticels are porous structures found on bark.

Complete answer :
Plants develop different mechanisms for respiration. Lenticel is one such structure. Lenticels are openings formed in the bark and the woody stems of dicotyledonous flowering plants. Lenticels help in gaseous exchange between outer atmosphere and inner tissues of the stem.

Additional information: All tissues outside the vascular cambium, constitute the bark.
Bark has two parts:
Outer bark: All the tissues outside the cork cambium are called cork.
Inner bark: The region between cork cambium and vascular cambium is called inner bark.
Lenticels are openings formed in the bark through which exchange of gases takes place. The cork cambium, instead of producing cork cells, forms irregular parenchymatous cells at each lenticel. These cells are loosely arranged with abundant intracellular spaces. These cells are known as complementary cells. Lenticels help in gaseous exchange between outer atmosphere and inner tissues of the stem. They are porous structures. Lenticels are found in the woody stems of dicotyledonous flowering plants.
Lenticels are seen as raised, oval or circular areas on the woody stems, roots and barks. Lenticels may be seen on fruits too. Example- apple and pear.
Lenticels may be discolored in case of mangoes.
Plants develop specialized structure for breathing in cases where there is absence of oxygen or less oxygen. Lenticels may be found on such specialized structures. Example- lenticels are found on pneumatophores or breathing roots of mangroves.
A global disorder among apples called ‘lenticel breakdown’ occurs in apples. The lenticels develop dark 1–8 mm diameter pits. This happens shortly after processing and packing. This condition happens in arid regions.
Lenticels are also present on tubers like potatoes.

Note: Lenticels help in transpiration too. However the amount of lenticular transpiration is quite low. The maximum amount of transpiration is carried out by stomata.