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Garden Talk

Bare branches of flowering dogwood against a bright blue sky, with round flower buds at the branch tips

Winter Tree Identification

By Katherine Hale

Marketing & Communications Assistant

How do you identify trees in winter? With most of the trees in the landscape now missing their leaves, it’s easy to think of a forest or garden as a collection of identical bare sticks with no way to easily distinguish between them, but nothing could be further from the truth. On the contrary, the winter landscape offers the unique opportunity for closer inspection, and it quickly becomes apparent that there’s more to these dormant trunks and branches than initially meets the eye.  

After a leaf falls, the imprint it made on the branch or stem from which it grew remains as a “leaf scar”—although unlike human scars, no injury to the tree is involved. Each kind of tree has a different kind of leaf scar, which can also be used as a form of identification. The leaf scars of common figs (Ficus carica) are particularly large and notable on the branches in winter, as are those of many species of deciduous magnolias (Magnolia spp.) and tulip poplars (Liriodendron tulipifera). By comparing the leaf scar of an unknown tree to pictures in field guides or on the Internet, one can easily make an ID.  

Close-up of umbrella magnolia twig with leaf bud and leaf scars visible

Although most trees are dormant during the winter, the buds containing the next season’s leaves and flowers are ready and waiting for warmer weather to unfold. The sealed buds can easily withstand freezing temperatures, but newly emerged leaves and flowers are extremely fragile, which is why fluctuations between warm and cool temperatures can be dangerous for the tree or wipe out an entire year’s worth of crops in a single night.  

However, these buds offer more than just protection from the elements—they also serve as a unique identifier of the species in question. Beech (Fagus spp.) leaf buds are long and pointy, with distinctive brown scales; they also tend to hold on to their leaves for much longer than other trees do, sometimes until the following spring. Oak leaf buds (Quercus spp.) are round and shorter, with several at each branch tip, while pawpaws (Asimina triloba) are small, black and fuzzy. Flower buds also come with their own distinctive shapes. The thin, pointed leaf buds of flowering dogwood (Cornus florida) are very different from the fatter, rounder flower buds.  

Although it’s less reliable, it’s also possible to identify trees via their bark. Many trees, such as lacebark elm (Ulmus parvifolia), paperbark maple (Acer griseum) and crape myrtle (Lagerstroemia spp.), are grown specifically for their distinctive, decorative bark. Bark is also an easy way to identify American sycamore (Platanus occidentalis). However, bark can also be tricky, as it can change color and texture as a tree ages, as is the case with red maple (A. rubrum), which transitions from smooth and silver when young to ridged and crackled when older. Because of this, it’s best to also look at other parts of a tree, just to be certain.  

Meanwhile, evergreen trees come into their own in winter, and they are worthy of study in their own right. These include many of the species associated with holiday greenery, like spruce, fir, and holly, as well as iconic southern species like “live oaks” (epitomized by Q. virginiana) and southern magnolia (M. grandiflora). While it is possible to identify all of these species via bark or buds, it’s usually easier and faster to look at the leaves, since they are present year-round. For example, many kinds of pine (Pinus spp.) can be identified by their needles—with both the length of the needles and the number per “bundle” (which botanists call a “fascicle,” due to its resemblance of a book) varying between species. 

Because leaves take a great deal of energy to make, conifers and other evergreens prefer to use theirs for as long as possible, and to shed them one by one rather than in one fell swoop. While this choice makes them more energy-efficient, and ready to start growing again whenever conditions are favorable, it also makes them more vulnerable to severe weather, especially ice storms, which can easily send a leaf-covered tree toppling to the ground. In the end, there’s no solution that’s better or worse than the other, only a series of trade-offs that shape plants over time.  

Buds, bark, evergreens and leaf scars are all elements that are usually overlooked during the growing season in favor of the flashier leaves and flowers, but they have their own particular elegance and beauty and are worthy of our time and consideration in their own right. From a botanical perspective, winter is a time of rest and recovery, as plants cease their annual growth and wait patiently for warmer times. From a human perspective, it’s an important reminder that the very limitations imposed by the season are an opportunity to get creative, look beyond the obvious, and appreciate the world around us.  

More Garden Talk Highlights

Photos from top: The canopy of a flowering dogwood (Cornus florida) in the Blomquist Garden of Native Plants, with the distinctive rounded flower buds clearly visible; close-up of an umbrella magnolia twig (Magnolia tripetala) in the Blomquist Garden with leaf bud and leaf scars; close-up of the trunk of lacebark elm (Ulmus parvifolia). All photos by Gabriel Campos, a graduate student in Duke's Nicholas School of the Environment.

Peeling gray bark of lacebark elm, exposing yellow-green wood beneath