Every winter I teach several tree identification classes to biology students. Cold or colder, it’s always outdoors, but if student evaluations are on the level, it’s always fun. Demonstrating how to tell one leaf-bereft hardwood from another is one thing.
Bark is not the best feature for identifying trees. Sure, white bark means birch, but some birches have black, yellow or reddish bark. Typical bark patterns, such as diamond-shaped furrows for ash, can be absent depending on site conditions and tree health. Cherry and ironwood bark have light-colored horizontal dashes called lenticels, but only on young wood. Not all hickories have shaggy bark. Bark may provide a clue, but it’s not to be trusted as a sole, or even a primary, source of information.
A better diagnostic tool is arrangement. Don’t get a vase; this means whether twigs grow opposite one another or are alternate on the branch. Most trees are alternates, so we focus on opposites: maple, ash and dogwood (MAD). Shrubs and small trees in the Caprifolaceae family, such as viburnums, have opposite arrangement. Remembering the phrase “MAD Cap” may help you keep track of who is opposite and who is not.
Smell is an honest indicator, but only for a few species. Twigs of yellow and black birch smell of wintergreen. Peel a cherry twig and you’ll get a whiff of bitter almond. Red and silver maple look similar, but the twigs of the latter smell rank when broken.
Since all our native dogwoods are shrubs, the opposite-tree category comprises only maple and ash. That would sure narrow things down, except stuff happens to trees that can cause confusion. Every twig on an ash or maple branch can be missing its “partner twig” on the other side of that branch. Breakage, fungal cankers, freeze damage and other things will do that, so don’t trust branch arrangement entirely.
So what can we rely on as an accurate indicator? Tree buds can tell us many things. Look closely. Are the buds opposite or alternate? Size, shape and placement are clues. Here are just a few examples:
- Beech have long, lance-like buds.
- Balsam-poplars have sticky, aromatic buds.
- Red (soft) 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.
- “Invisible” black locust buds hide under the bark.
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 few scales, which vary greatly in size. Sugar maple buds have many, uniform scales. Butternut and hickory buds have no scales.
For more details on tree identification, see Cornell’s book “Know Your Trees,” available as a free pdf download, or call your local Cornell Cooperative Extension office.