By Kendrick Fowler
When I’m out wandering through the woods with my camera at this time of year, one of my favorite things to do is to look for interesting patterns to photograph in the bark of trees. Often, I find myself most drawn to birches (Betula spp.) and cherries (Prunus spp.), whose bark is streaked with long, skinny lenticels.
Lenticels do more than just form a pleasing pattern: they are pores through which trees exchange gases (especially carbon dioxide, oxygen, and water vapor) with the atmosphere. This brings a question to mind: why are the lenticels of birches and cherries so large and conspicuous compared to those of other trees?
Unfortunately, I do not have an answer to share with you! According to a recent review (Rosner & Morris 2022), little research has been conducted on lenticels and their function, and the factors that influence the size, shape, and number of lenticels that a tree develops remain poorly understood.
According to Rosner & Morris, it seems fairly clear that lenticels are important to trees for respiration and water management, but it is not known whether trees can open and close their lenticels to the atmosphere as they can their stomata (the pores in their leaves), how environmental conditions influence the number, size, and distribution of the lenticels a tree develops, or whether there are differences in how permeable lenticels are among tree species or even among different parts of the same tree. Lenticels also seem like they could be places where trees would be vulnerable to attack by insects or fungi, and while some lenticels seem to show defensive adaptations (for example, the concentrations of defensive chemicals may be higher in lenticel tissues), the importance of lenticels in plant defense remains almost entirely unstudied.
It seems to me that the lenticels’ mysteriousness makes them all the more intriguing, and I look forward to the next time they will catch my eye as I wander through the woods.
Thanks as always for reading, and have a happy holiday season!
References
Rosner, S. and H. Morris. 2022. Breathing life into trees: the physiological and biochemical functions of lenticels. IAWA Journal 43 (3): 234–262. DOI: https://doi.org/10.1163/22941932-bja10090.
Progress of the Seasons Journal 