Bark serves as a reliable identifier for trees, particularly during the winter months when deciduous species have shed their foliage. The bark of trees within the Acer genus, commonly known as maples, displays unique characteristics that allow for accurate identification even without the distinctive five-lobed leaves. Understanding the developmental stages and specific textures of maple bark is key to distinguishing one species from another.
General Development of Maple Bark
Maple bark undergoes a significant transformation as the tree matures, making the age of the specimen an important factor in identification. Young maple saplings typically feature bark that is relatively smooth and light gray, sometimes with a greenish or brownish tint. This initial smooth texture provides limited species-specific clues and is often compared to the bark of a young American Beech.
As the trunk increases in diameter, the outer bark (rhytidome) breaks apart under pressure, forming vertical ridges and channeled depressions (furrows). Mature maple bark generally develops plates or strips that run longitudinally down the trunk, unlike the blocky textures seen in some other hardwoods. These plates may adhere tightly or begin to curl and peel slightly at the edges, offering the first clear indicators of the tree’s identity.
Species-Specific Bark Profiles
Sugar Maple (Acer saccharum)
The bark of the Sugar Maple is the most recognizable among native maples due to its rugged texture on older trees. Mature specimens develop dark gray-brown bark that is deeply furrowed, creating long, irregular vertical ridges. These ridges often interlock, giving the trunk a plated appearance that adheres firmly to the wood.
The furrows are deep and pronounced, sometimes appearing scaly along the edges of the vertical plates. On old trees, the edges of these plates may lift slightly, contributing to a somewhat shaggy look without the loose, stringy quality of other maples. Younger Sugar Maple bark remains grayish and smooth for a longer period compared to other species, only gradually developing its characteristic deep furrows.
Red Maple (Acer rubrum)
Red Maple bark is initially smooth and light gray on young trees, which can lead to misidentification with American Beech. As the tree ages, the bark develops shallow fissures that break the surface into long, vertical strips or flaky plates. These plates often peel slightly away from the trunk, giving the bark a shaggy or flaky appearance.
Flaky plates often reveal an inner bark that is reddish or pinkish in color. The bark generally darkens to a darker gray or brown with age, but the underlying reddish hue can be visible in the furrows or where the outer bark has peeled. This vertical striping and flaking pattern is more delicate and less deeply furrowed than the bark of a mature Sugar Maple.
Silver Maple (Acer saccharinum)
The Silver Maple is known for developing the shaggiest bark of the maples, particularly on older trunks and large branches. The bark is light gray or silvery when young, and this color persists in the deep furrows of mature trees. As the tree grows, the outer layers separate into long, thin, scaly strips that are loose and peel away freely from the trunk, often only remaining attached at the center.
These long, vertically peeling strips create a distinctly shaggy or “stringy” texture that is characteristic of the species. The loose strips are a reliable way to differentiate this species from the more tightly adhering bark of the Sugar Maple. The contrast between the dark, deeply fissured furrows and the lighter, curling strips contributes to its unique appearance.
Norway Maple (Acer platanoides)
The Norway Maple, a non-native species common in urban settings, exhibits bark that is dark brown to nearly black on mature trees. Its bark is tightly ridged and remains relatively firm and close-fitting to the trunk compared to the peeling barks of Silver or Red Maples. The ridges are often narrow and somewhat interlacing, forming a cross-hatched pattern that is less deeply furrowed than the Sugar Maple.
The bark’s color is darker than most native maples, contributing to its distinct profile. While it develops furrows and ridges, the overall texture feels compressed and firm, rarely exhibiting the loose, peeling plates or shaggy strips of other Acer species. This tight, dark, and often blocky appearance sets it apart from the more vertically striped or shaggy native maples.
Differentiating Maple Bark from Common Look-Alikes
Distinguishing maple bark from other common trees in winter requires focusing on the unique vertical patterns that characterize the Acer genus. A common misidentification involves Ash trees, particularly White Ash, which also have opposite branching but develop a distinct bark pattern. Ash bark typically features deep, uniform furrows that intersect to create a characteristic diamond or lattice-like pattern, contrasting with the maples’ predominantly vertical strips and ridges.
The bark of certain Oak species, such as White Oak, may also develop deep ridges, but their texture is often described as blocky or thick, with scaly plates that are horizontally broken. This contrasts with the maples’ tendency towards long, vertical fissures. American Beech bark maintains a smooth, tight, bluish-gray texture throughout its lifespan, lacking the vertical ridges, plates, or furrows that define mature maple trees.