Identifying ash and maple trees in winter

December 20, 2011
View a slideshow of ash and maple twigs, buds, and bark.

In autumn we travel great distances to find the brightest fall palette. But when winter arrives and our primary means of identifying deciduous trees drops to the forest floor, we tend to turn our focus to their coniferous neighbors. Yet naked trees offer an opportunity to deepen our knowledge and appreciation for the forest’s many species. Identifying trees without leaves is tricky business, though. Here’s how to get started with two of the Northeast’s dominant trees: ash and maple.

For Michael Wojtech, author of Bark: A Field Guide to Trees of the Northeast, the tree identification process resembles a funnel. “It’s always trying to get from the wide brim as far down as you can,” he says. “Any narrowing down that you can do is a success.” The first big clue is the tree’s structure. Hardwood species have two primary structures: opposite and alternate. The former features sets of branches growing from the trunk across from each other at the same height. An alternate structure has branches that grow in an asymmetric pattern. In both cases, the leaves and buds will also grow this way. Most Northeastern tree species feature an alternate structure. Ash and maple are two prominent exceptions. (Dogwood, a rarity within forests, and the non-native horse chestnut, often planted in urban areas, are two others found in the Northeast.)

Leaves offer clues even in their absence. Compound leaves grow in dense clusters of leaflets and require robust twigs for support. An ash leaf, for example, usually consists of 5 to 11 leaflets. Simple leaves, like a maple’s, are individual and need only the support of delicate twigs. Once the opposite structure of a tree is identified, Wojtech recommends a simple second step: Just look up into the branches. It’s an ash, he says, “if you’re looking up and you see big fat twigs. The actual thickness is going to be dramatically different.”

Bark and buds
Next, it’s time to identify the species. Unfortunately bark, perhaps the most obvious feature, doesn’t always offer clear clues. Bark characteristics vary greatly with age. A single specimen can exhibit several distinct bark patterns between its base and the higher (and younger) reaches of the trunk. Weather exposure, blight, and other disturbances can also affect a single tree differently on different portions of the bark. Look to pair your observations of the bark with what you can see of the buds on low-hanging branches. Examining these two features should tell you if you’re looking at one of the following species.

White Ash: Soft bark develops diamond-shaped fissures with age. Brown buds emerge inside a C-shaped leaf scar.

Green Ash: Similar to white ash, but with shallower fissures in mature bark. The bud appears with a D-shaped leaf scar. (Black ash features even more shallowly furrowed bark and darker buds.)

Red Maple: Smooth gray bark breaks into irregular fissures with age. Strips of bark can begin to detach at either end, curling outward. Red winter buds give way to red and yellow flowers in early spring. (Sometimes confused with the less common silver maple, which features dense bud clusters.)

Sugar Maple: Young bark can feature a mosaic of cracks, like the surface of glazed pottery. Vertical fissures with horizontal cracking develop with age, and thick plates of bark can begin peeling along one edge. Buds feature layers of tiny scales.

Striped Maple: Bright green bark laced with vertical white stripes sets this species apart. Ages into a darker, reddish brown bark with black vertical lines, and should be readily identifiable.

Red herring
With leaves off the trees, there’s an obvious temptation to peek at them on the ground. Be wary. “To use the leaf alone can be a treacherous path,” Wojtech says. Weather and wildlife can shuffle the forest floor so there’s no assurance that the leaf you’re studying fell from above. If you find abundant evidence of just one species, fallen leaves might help. But if you see several varieties, you’re better off avoiding the temptation.

Adding tools
Each step in identifying a maple or ash can be transferred to the study of other species—you’ll just need more information, such as a good field guide, to help you reach an accurate conclusion. But with some study and legwork, your skills of observation will quickly develop. “Once you know [clues] are there, it’s second nature,” Wojtech says. “You don’t have to look as much the next time. It just happens.”

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