Lenticel

lenticel [ LEN-tuh-sel ] noun: a pore or aggregation of cells penetrating the surface (as of woody plant stem or trunk, or skin of apples, pears, potatoes, mangoes, avocados) and through which gases are exchanged between the atmosphere and the underlying tissues

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What do the bark of a spicebush, the skin of an apple, and the skin of your face have in common? Not only do they all offer protection from outside elements, they have small openings that allow the exchange of gases and water vapor between the surrounding atmosphere and the stem, fruit, root, or flesh underneath. In the plant world, we call that pore a lenticel.

The skin, or cuticle, of plants prevents excessive loss of water vapor, but the lenticels permit some of that and also the exchange of oxygen (entering) and carbon dioxide (exiting) the stem or fruit. These small openings can also, unfortunately, be the entry point for fungal spores and other disease-causing organisms or substances.

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Lenticels on Fruits and Tubers

The lenticels on apples look like tiny flecks or dots, or even tiny starbursts. Apples are subject to lenticel diseases and fruit rot (e.g. black rot, white rot); many of the apples we buy in supermarkets are lightly coated with edible wax, which helps keep them fresh. The small slit-like lenticels of potato tubers are necessary for the exchange of gases as well, but also allow access to pathogens that affect the marketability, and in serious cases, the edibility of the potatoes. Soils that are too wet and storing potatoes that are not adequately dried enlarge the lenticels and contribute to the tubers’ vulnerability to disease. Avocados, whether smooth-skinned or bumpier, as in the ‘Hass’ variety, have high respiration rates compared to many other fruits. Although avocados are often attacked by anthracnose infections in the field, further research is needed to determine if lenticel damage caused by handling is only aesthetically consequential, being most visible in unripe avocados. (Everett et al. 2008) 

Left to right: Fuji apple, Honeycrisp apple, russet potato, potato with rotten tissue, ripe ‘Haas’ avocado, unripe ‘Haas’ avocado.

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Lenticels on Trees and Shrubs

Lenticels on woody bark stems or trunks manifest as spots or raised bumps, stripy scarifications, or in more mature plants, sometimes corky thickenings with definitive patterns. They can be longitudinal (in the same orientation as the main stem or body of the plant) or transverse (crosswise to the orientation of the main trunk, stem, or body of the organism). Often their appearance on the bark helps with tree identification, especially in deciduous trees in winter. On many woody plants, though, lenticels are inconspicuous or visible only on a species’ younger stems.

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References

Everett KR, Halletta IC, Rees-Georgea J, Chynowetha RW, Pakb HA. 2008. Avocado lenticel damage: The cause and the effect on fruit quality. Postharvest Biology and Technology 48(3):383–390.

Robinson A, Secor G. 2016. Managing Lenticel Spot on potato tubers. A1822. North Dakota State University. (accessed January 15, 2021).

Shane B. 2012. Lenticel infections and bitter rot of apples. Michigan State University Extension.

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