Humans have a penchant for accessories in the wardrobe, home décor, and the garden. Plants offer an array of seasonal accessories adding interest with flowers, foliage, fruit, fragrance, pods and bark.
When deciduous trees shed leaves and expose their bark each autumn, they reveal one of the most attractive landscape accessories, lenticels. Lenticels are porous clusters of cells on the surface bark of woody plants.
Looking at Lenticels
Lenticels look like slits on the outer surface bark of twigs, trunk and roots of trees. Various observers have described them as warts, bumps, splits, fissures, even mouths or lips. Although all trees have lenticels, some tree species have more conspicuous lenticels than others.
The color, shape, size, density, and distribution of lenticels depend on the species. Wild and cultivated fruit trees like plum, apple, pear and peach have prominent lenticels.
Age of a tree affects lenticel characteristics too. Lenticels on young branches of a cherry tree look more like dots while older cherry tree lenticels spread horizontally.
Bark rubbings are not only good at capturing the texture of the outer bark but also present lenticel shapes and patterns.
Inspecting lenticels with a magnifying lens or macro camera lens captures their composition.
Identifying Trees by Lenticels
Lenticels are one of many clues to help identify deciduous trees in winter. Boy and Girl Scouts and wilderness groups learn to look for lenticels on twigs and trunk.
Keyed tree identification field guides may use lenticels as one category of clue.
Function of Lenticels
Lenticels, critical to a tree’s cellular respiration, function as aerating tissue allowing for the entrance of oxygen and exit of carbon dioxide during respiration and permitting the exit of excess water absorbed by the tree.
The lenticel air conditioning system of the tree provides much needed ventilation for the living vascular bundles within the tree since the bulk of the outer bark is made of alternating layers of suberin, an insoluble lipid, and wax creating an impermeable barrier for diffusion of gases.
To demonstrate that bark lenticels are in contact with the interior cellular processes of a stem, snip a woody twig from a tree or shrub. Using flexible tubing connect one end of the twig to a bicycle pump. Completely submerge the twig in water and force air into the twig. Watch for the release of bubbles through the lenticels.
Blocking Lenticels
If lenticels are blocked, oxygen depletion occurs and tissue dies. Lenticels are blocked by flooding or prolonged submersion of trees in water on flood plains or in swamps. To compensate some trees put forth adventitious roots from enlarged lenticels below the water’s surface. These roots replace soil roots that die from loss of oxygen. Other trees like the bald cypress send up ‘knees’ covered in lenticels which act as respiratory organs to aid aeration of inundated roots.
Landscaping with Lenticels
Lenticels add aesthetic beauty to the landscape, especially in the bare bones of winter. Just as grain and color of furniture and floor woods influence the direction of interior design, bark with lenticels can be selected to create interest in the exterior landscape.
Making an inventory of trees with prominent lenticels on one’s property is a starting point. Tree walks in state and national parks and arboretum near one’s home give additional insight into species acclimated to your region. Local forestry agents and tree nursery owners can suggest species for your site.
The following trees are known to have visible lenticels with landscape interest:
- Birches
- Cherry
- Crabapple
- Chinese pistachio
- Elderberry
- Eastern redbud
- Hackberry
- Pear
- Plum
- Red maple
- Sassafras
- Willows
Lenticels and Pathogens
Lenticels are natural openings on tree bark. Openings on bark whether natural or formed by man, another animal or machine make the tree susceptible to pathogens. Bacteria, fungi, and viruses can enter trees through the lenticels.
Cankers, localized dead areas on trees and shrubs caused by fungi or bacteria, often enter tree tissue through lenticels.
Lenticels are a lovely winter garden accessory and a yearlong necessity for trees.
Arlene Marturano - Arlene Marturano, an educator, consultant, master gardener, and writer advocates gardens as a context and gardening as a tool for ...
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