A lenticel is an airy aggregation of cells within the structural surfaces of the stems, roots, and other parts of vascular plants. It functions as a pore, providing a medium for the direct exchange of gasses between the internal tissues and atmosphere, thereby bypassing the periderm, which would otherwise prevent this exchange of gases. The name lenticel, pronounced with a soft c, derives from its lenticular shape. The shape of lenticels is one of the characteristics used for tree identification.

Formation

Lenticel formation begins during the development of the first periderm. In the stem, they usually appear below a stoma

Stoma

In botany, a stoma is a pore, found in the leaf and stem epidermis that is used forgas exchange. The pore is bordered by a pair of specialized parenchyma cells known as guard cells that are responsible for regulating the size of the opening...

 or group of stomata. Lenticels are found as raised circular, oval, or elongated areas on stems and roots. As stems and roots mature lenticel development continues in the newly forming periderm found at the bottom of cracks in the bark

Bark

Bark is the outermost layers of stems and roots of woody plants. Plants with bark include trees, woody vines and shrubs. Bark refers to all the tissues outside of the vascular cambium and is a nontechnical term. It overlays the wood and consists of the inner bark and the outer bark. The inner...

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Fruits

Lenticels are also present on many fruits, quite noticeably on many apples and pears. On European pears

European Pear

The European Pear, Pyrus communis, is a species of pear native to central and eastern Europe and southwest Asia. The European Pear is one of the most important fruits of temperate regions, being the species from which most orchard pear cultivars grown in Europe, North America and Australia have...

, they can serve as an indicator of when to pick the fruit, as light lenticels on immature fruit darken and become brown. Certain bacterial and fungal infections can penetrate fruits through their lenticels, with susceptibility sometimes increasing with its age.