Most people who love nature don’t restrict their outings to days when it’s sunny and over 60 degrees: We’d never get outside in Ohio. On a winter hike through your favorite forest, you may see many trees and shrubs that are unfamiliar.
How can you learn to identify these plants in winter? Answer the following questions, and test your knowledge of winter identification.
Q: This huge tree, which often grows along streams, has attractive brown mottled bark. Patches of the bark often slough off the trunk and large branches to reveal the bright white bark beneath. Name this tree.
A: The native American sycamore is the only massive tree you will see with this kind of bark. Sycamore’s cousin, the London plane tree, has mottled bark with green hues and yellow bark underneath instead of white.
Bark characteristics are helpful in identifying many trees in winter. Black cherry has dark bark that’s flaky like potato chips, white oak has striped, shaggy bark, and of course shagbark hickory peels from the trunk in long, narrow strips. And who could forget the smooth, gray bark of beech, compared by some to the skin of an elephant?
Q: Of course, not every tree is easy to identify from bark alone. As you stop to observe a twig close up, you notice that the leaf scars (marks on the twigs where the leaves used to be attached) are arranged opposite one another. What kind of tree might this be?
A: Most trees have alternate leaf arrangement, which means the leaves are not attached to the twigs directly opposite from one another. When the leaves are attached in an opposite arrangement, the choices are relatively few. Keep in mind the phrase “Mad Cap Horse,” which stands for Maple, Ash, Dogwood, CAPrifoliaceae (plants in the honeysuckle family, including viburnum) and HORSE chestnut (and buckeye). All of these plants have opposite leaf arrangement.
Q: Another plant you notice at the edge of a marshy area has neither opposite nor alternate leaf arrangement. Instead, the leaf scars are whorled around the branch, similar to opposite arrangement but with three scars around the twig instead of two. What plant is this?
A: Very few woody plants have whorled leaf arrangement. The two we are likely to see in Ohio are catalpa and buttonbush. Buttonbush is a native shrub, common in wetland areas.
Q: On your walk, you notice that twig color often stands out. Some twigs are yellow, some bright green and some deep red. What are some trees and shrubs with colorful twigs?
A: One of my favorite trees, sassafras, has bright green twigs on newer growth. Some willow twigs are yellow, shrub dogwoods are often grown for their red or yellow twigs, and the newer growth on red maple can sometimes be strikingly red. Distinctive twig color is more the exception than the norm, but in a few plants this characteristic can aid in identification.
Q: Two of the plants you see as you walk along have a bluish cast, but upon closer observation, you note that this blue color on twigs seems to rub off. What’s going on?
A: This waxy, blue coating, called “bloom,” is common on boxelder, brambles and flowering dogwood.
Q: One twig you examine has a strong odor when scratched. What are some trees and shrubs with distinctive odors?
A: Some plants can be identified by their pleasing spicy odor, such as sassafras, spicebush (Lindera benzoin), and sweetshrub (Calycanthus floridus). Sweet birch smells like wintergreen, due to the oil in the twigs and small branches. Tulip tree and cucumber tree, both in the magnolia family, have fragrant twigs. Other less pleasing-to-smell trees include the pungent black cherry and the acrid tree-of-heaven.
Q: Some twigs have small, freckled dots on the bark. What are these dots, and how can they help identify the plant?
A: These dots, called lenticels, serve as pores for gas exchange on twigs. Black cherry and European buckthorn are two plants with numerous small, white lenticels. Other plants, like buttonbush, have large, slit-like lenticels.
Q: Buds are a common means of identifying trees and shrubs in winter. Name two trees with distinctive buds.
A: The first tree that comes to mind is the saucer magnolia, which has large, fuzzy bud scales (scales are the bud coverings). The buds of this tree are so fuzzy, in fact, that some people confuse this tree with pussy willow. (The fuzzy part of pussy willow is not a bud but a flower.)
Other trees with distinctive buds include the sticky buds of horse chestnut, the duck-bill-like buds of tulip tree, the clustered buds of oaks, and the blood red buds of basswood.
Q: Which leaf scar seems to be smiling at you?
A: If you look closely at a tree’s leaf scar, you’ll notice a consistent pattern within that leaf scar among plants of the same species. The vascular bundles are the tree’s conductive tissue, transporting water and sugars during the growing season. These bundles continue from the twigs into the leaves; when leaves drop in autumn, the vascular bundles leave a pattern in the leaf scar known as the “bundle scar.” On a butternut, these bundle scars look like two eyes and a smile. Willows have three bundle scars on each leaf scar. Becoming familiar with these patterns can aid in winter tree identification.
Q: What are some other tree characteristics that can help identify a plant in winter?
A: The presence of cones, catkins and thorns may lead you to a larch, filbert or honey locust. Of course acorns will lead you to oaks (which are difficult to specifically identify without the acorns), and pods may lead you to redbud or Kentucky coffee-tree. Plant keys will often ask for information on the twig’s center, or pith, such as its color or texture.
Q: Name four references to help with winter identification of trees and shrubs.
A: These books are always on my reference desk in winter. The easiest and least expensive book is a short key to winter trees called Winter Tree Finder, by May Theilgaard Watts and Tom Watts. Fruit Key and Twig Key to Trees and Shrubs by William Harlow is also very reasonably priced (around $6) and very thorough.
For more detailed identification information on more than 1,000 species, consult Winter Botany, by William Trelease. Woody Plants of Ohio by E. Lucy Braun is an excellent overall reference that can be used for winter or summer identification.
Denise Ellsworth directs the honeybee and native pollinator education program for the Ohio State University. If you have questions about caring for your garden, contact her at 330-263-3700 or click on the Ask Denise link on her blog at www.osugarden.com.