Lenticels

Lenticels are porous tissues used in plant respiration.

Plant respiration involves exchanging oxygen, carbon dioxide, and water vapor as part of photosynthesis and other cellular functions to generate or release energy.

​The words ‘lenticel’ and ‘lenticular’ refer to the more common lentil-shape of these openings, but theses raised areas can be round, oval, or elongated. In some cases, such as silver birch, lenticels appear as horizontal cracks.

Dark horizontal lenticels on silver birch (Sue Sweeney) CC BY-SA 3.0

There are two types of lenticels: those found in the stems, trunks, and roots of woody plants and trees, and those found in the skin of certain fruits, such as apples.

Fruit lenticels

Many apples and pears, in particular, have fruit skin lenticels. These are the tiny nicks of color seen on the skin. These lenticels start out light colored and then darken as the fruit reaches maturity and is ripe for picking. This darkening occurs because of the formation of cork cells. These openings are often the site of failing stoma, broken off trichomes, or other points of early damage, rather than planned growth. The number of lenticels seen on pome fruits can vary by species and by the availability of water during early development.

Lenticels on apples (Rasbak) CC BY-SA 3.0

Lenticels on pear (Augustus Binu) CC BY-SA 3.0

Bacterial and fungal disease can enter the fruit through these openings. There is a global skin disorder of pome fruits, called ‘lenticel breakdown’, in which 1-8 mm pits develop at the lenticels just after processing.

Tree lenticels

Trees and other woody plants have lenticels in their bark (periderm), both above and below ground. These openings facilitate the necessary exchange of oxygen, carbon dioxide, and water vapor. Since different species have uniquely shaped lenticels, knowing the characteristic shape of a tree’s lenticels can help in identification

Lenticels on birchbark cherry (Rosser1954) Public Domain

Trees growing in low oxygen environments, such as mangroves, have lenticels on specialized roots. Grapes, on the other hand, have lenticels on their pedicels, or flower stems. Grape lenticels react to changes in temperature, rather than oxygen levels.

Did you know that potatoes have lenticels?

Now you know.