Tree ID: How To Be Your Own Best Detective

Giant tulip poplar in Orange, Virginia

I remember the first time I recognized the value of knowing a tree’s name. I was walking with a friend along the C & O canal in Great Falls, Maryland when she began identifying the trees around us. As we passed, she stopped to observe different species, remarking on their visible characteristics and quality of growth. Suddenly, the woods took on an entirely new dimension for me.

Most of us feel more comfortable in public when we know people’s names and a little bit about them. I learned that day that the same goes for trees. Acknowledging each by name allowed us to communicate with and about them, opening a door into a world that had until that moment been only green.

Elm tree

Knowing a tree requires undivided attention

I’ve made great strides learning names of trees over the past decade. Still, I remain frustrated by the ones I don’t know. Just when I think I’ve nailed it, someone will present me with an oddball leaf I can’t readily identify. And, as a garden designer, most clients expect me to be not only an expert on shrubs and perennials, but trees as well.

So recently, I was happy to learn that the Audubon Naturalist Society (ANS) was offering a full-day lecture on native tree identification in Chevy Chase, Maryland. The lecture was held in a beautiful old brick home that serves as their location. Girded on all sides by dense woodland, the property features some of the most magnificent mature trees in Maryland.

Audubon Naturalist Society headquarters in Chevy Chase, Maryland

Our instructor, senior naturalist Stephanie Mason began our lecture with this quote from Edgar Allen Poe:

To observe attentively is to remember distinctively.

OK, Poe was speaking about investigating murders, not trees, but Mason feels the quote applies. To be a good tree identifier, you need to first become a good observer. She cautioned that even the experts don’t expect to identify everything correctly.

“It’s a big plant word out there,” Mason said. “If you know how to use a field guide, you’re already on your way. You have to go out and observe again and again. And then go out and observe again.”

And with that, we were off to the races.

Dried seedpods (samaras) of a maple

Five easy steps to tree identification

There are many characteristics that can be used to identify trees, including overall size and shape of the tree, size, shape and arrangement of leaves, buds, bark , fruit and flowers. Most people use a combination of the above. Still, when attached to the tree, leaves are the most common identifying feature. We started by snapping off a twig with some leaves on it and asking ourselves these questions:

Step 1. Are the leaves single or compound?

A single leaf is attached to the twig on its own, while a compound leaf consists of a number of leaflets that together, comprise one leaf.

Step 2. How are the leaves arranged on the tree?

One important tool to identifying trees is to determine the placement of the leaves on the tree. Are the leaves growing opposite or alternate to each other on the twig?  To aid in the task, Mason shared with us a useful mnemonic. (This is used for remembering which trees have opposite leaves in our area.)

MAD HORSE    Or, Maples, Ashes, Dogwoods and Horse chestnut.

Step 3. What do the leaf margins look like?

Next is to zero in on the leaf itself. Are the margins smooth, wavy, toothed or lobed? (In some cases, you may need a magnifying glass to better observe the leaf margins.)

Step 4. What is the veining like on the leaf?

Turn over the leaf and look at the veining. There are two types of veining that can occur. Palmate leaves have veins that spread outwards from a central point, just like fingers on a hand. A maple leaf is palmately veined.

Pinnate leaves have veins that extend outward from a central spine, like a feather An oak leaf is pinnately veined.


Step 5. What do the terminal buds look like on the twigs?

This simple step often helps ID the tree the fastest. For instance, the terminal buds of flowering dogwood trees have a distinctive onion shape.

Terminal bud of Cornus florida, Flowering Dogwood/Stephen J. Baskauf

The Dichotomous Key

Dichotomous keys are useful tools that help people identify things in the natural world. The keys consist of a series of choices, A or B, that lead the user to the correct name of the species. Our tool for the day was ‘Common Native Trees of Virginia’, but there are many other dichotomous keys for identifying items from all over the world. Tree ID experts use them all the time.

The keys always start with the same choice, Choice Number One. Once you have determined which answer best describes your specimen, you go to the number where the choice directs you. You follow the numbers in this way, continuing to read and select answers until you arrive at the name of the tree. It’s a lot like a treasure hunt and an invaluable resource for deciphering plant life in your area.

Interested in learning more? There are dichotomous keys for just about everything. Look for one that applies to trees in your area and get started! (Click the link above for a list of what’s available on Amazon.) I guarantee it will open up a whole new world.



Leave a Reply