Tips for Winter Tree ID

[Paul J Hetzler]

Tree Buds: Honest Friends

How to distinguish one leaf-bereft hardwood from another in winter is more of a challenge than summer tree ID, but there are practical reasons – and a few offbeat incentives – to tell one species from another in the dormant season. Hikers and skiers can benefit from such a skill, and in survival situations, hydration and warmth may depend on it. And if you’re among those who adore wintertime camping, you can have more fun when you know common woody species.

In late winter/ early spring, a pathogen-free beverage flows from sugar, silver, and red maples when temperatures rise above freezing in the day. A bit later in the spring yet prior to leaf-out, our native white (paper), yellow, black, grey, and river birches yield copious, healthful sap as well. The same can be said for wild grape stems, although it’s crucial that one can recognize other vines out there like Virginia creeper and poison ivy.

Being able to tell native shrub dogwood and Viburnum from invasive honeysuckle, Euonymus, and buckthorn may score you some tasty dried berries, and save you from the nasty effects of consuming the wrong ones. If you need fuel wood in a hurry, basswood won’t help, but ash, which has similar bark, definitely will. Black and pin cherry also burn respectably when green.

Foliage is front and center when you crack open a typical field guide. Without such a luxury, we have to look more closely. Bark comes to mind, and while sometimes helpful, it’s not always reliable: bark characteristics change as trees age. Not all hickories have shaggy bark, and the majority of birch species aren’t white-barked. Cherry and ironwood have lenticels on young wood only. Even the characteristic diamond-shaped furrows of ash bark may look different in some conditions.

A better diagnostic tool is arrangement: whether or not twigs grow opposite one another on the branch. Most trees have alternate twig growth, so we’ll focus on opposites: maple, ash and dogwood, or “MAD.” Shrubs and small trees in the family Caprifolaceae, such as viburnums, are opposite, too. The prompt “MAD Cap” may help keep track of who’s opposed and who’s in favor.

All our native dogwoods are shrubs, so maple and ash are the sole members of the opposite-tree club. You’d think that would simplify things, but twigs on any given ash or maple branch are frequently missing some (or at times many) “partner twigs” which are supposed to be opposite them. Wind, ice, pathogens, and other things are apt do that, so don’t trust branch arrangement entirely.

Fortunately for us, buds, like Vulcans, cannot lie. Look closely at a twig to see if the buds are opposite or alternate. Bud size, shape and placement will give further clues. Beech have long, lance-like buds, while those of balsam-poplars are sticky and aromatic. Red and silver maples have puffy, reddish buds. Sugar maple buds are brown and conical, like a sugar cone. Oaks have clusters of buds at the end of each twig. Black locust buds are “submerged” under the bark.

Location gives us some clue about tree ID, too. Riparian zones and other low-lying wooded habitats which are seasonally flooded are not likely to produce healthy sugar maple, white ash, red oak and white pine. On the other hand, red & silver maple, green & black ash, bur oak, white cedar, eastern hemlock, and elm will thrive in those types of places. Invasive and non-regional species like buckthorn, Norway maple and boxelder may show up on sites with a history of disturbance.

Shade-tolerance is of trifling use, as “intolerant” species can hang on a long while as they are shaded out by competitors. Size helps, but in one direction:  If faced with a specimen of unusual girth or height, it rules out short-maturing species like American hornbeam (musclewood, ironwood) and hawthorn.

Even the health profile of a species can be an aid. The presence of black-knot lesions indicates a cherry tree, for instance. A towering hardwood with a crop of dark “tennis balls” throughout its canopy is a hickory that is infested with Phomopsis gall disease. A deep, slanting scar on the lower trunk of a hardwood is likely the calling-card of a sugar-maple borer.

Smell is an honest indicator, but it only works for a few species. Yellow & black birch twigs smell and taste like wintergreen. Peel a cherry twig and you’ll get a whiff of bitter (cyanic) almond. Most features of red and silver maple twigs are very similar, but those of silver maple smell rank when broken.

Inside each bud is an embryonic leaf (and/or flower). To protect their tender charges, most tree buds have overlapping scales that open in spring. Basswood buds have two or three scales, which vary greatly in size. Sugar maple buds have many, uniform scales. Butternut and hickory buds have no scales, but depend on a bit of fuzz to guard leaf embryos. All in all, the best winter tree ID tools are buds. It would be a sad world if we couldn’t count on our buds to tell the truth.

For more details on winter tree ID, the booklet Winter Tree Finder is nice, and Cornell’s book Know Your Trees is a free download: (http://www.uvstorm.org/Downloads/Know_Your_Trees_Booklet.pdf).

An ISA-Certified Arborist since 1996, Paul Hetzler wanted to be a bear when he grew up, but failed the audition. Having gotten over some of his self-pity concerning that unfortunate event, he now writes about nature .