Joe Stavish, Tree Pittsburgh’s education director, often takes to social media to teach people about trees. On an early December morning, about a dozen people joined him in person to learn to identify tree species in the city's historic Homewood Cemetery.
A cemetery may seem like an odd choice for this event, but Stavish said Homewood is one of just 23 cemeteries in the U.S. that’s an accredited arboretum. That means many of the trees on the 200-acre property are labeled, and they provide education and funding to maintain, plant and upkeep the trees that are on the grounds.
Winter might also seem like the wrong time of year to try to learn about tree species. But Stavish said there’s an advantage in the colder months.
“Winter is a great time to look at the silhouette of trees,” Stavish said. “A lot of trees have different shapes which are hidden by the leaves in the summertime.”
Not all evergreens are pines
Stavish said the Homewood Cemetery is known for its collection of conifers. He said many people see a green tree in the winter months and assume it’s a pine tree. While pine trees are evergreen conifers, not all conifers are evergreen — though many are. Conifers are cone-producing trees, said Stavish, which are gymnosperms, meaning they produce a naked seed. They don’t produce flowers and fruits like deciduous trees.
Stavish showed the group two tall confers growing side by side in the cemetery. Instead of needles, they had green “scale leaves,” which he said look like fish or snake scales. These arborvitae trees (Thuja occidentalis) are larger than most planted in residential yards to provide privacy. One drawback is that deer love to eat arborvitae in the winter months, so Stavish suggested a fence to protect the bottom leaves and branches.
Be a nature detective
Stavish said we can look under trees to help identify them. Sometimes leaves have fallen off the branches to the ground, but leaves might have been blown by the wind from another tree. Stavish said to look close to the trunk for a better chance of identifying the right leaves, seeds or pods.
A huge northern red oak (Quercus rubra) found in the Homewood Cemetery is pushing up grave markers from the late 1800s. Stavish said it might have been planted there before the graves were put there, or might have been a young tree then. Either way, Stavish said it’s likely one of the oldest red oaks in the city.
Stavish identified it from the acorns found around its trunk. A few leaves still hanging on the tree were also clues. He said all oaks are either in the red oak or white oak family. If the lobes of the leaf are pointed or have bristle hairs on them, the tree is in the red oak family. If the lobes are rounded, it’s in the white oak family.
Opposite or alternate?
Another way to ID trees in the winter months is by their branch and bud patterns, which can be either opposite or alternate, Stavish said. He stopped under a tree during the walk to point out the easy trick.
“When I walk up to this tree, I can see one large bud on the end, but then I see two smaller buds here,” he said. “And they’re opposite of each other.”
The buds are dormant during the winter, but still visible. He also pointed out that the leaf scars, from where the leaves broke off, were opposite of one another.
Stavish said to remember the deciduous trees in Pennsylvania with opposite branches, use the phrase “MAD chestnut.” “M” is for maple; “A” is for ash; “D” stands for dogwood (though there is an exception); and “chestnut” stands for horse chestnut (Aesculus hippocastanum). That’s the tree the group was standing under. Buckeye trees are also opposite leaf and branch trees.
Stavish said you can tell the difference between a horse chestnut tree, originally brought from China, and a native buckeye tree, by their seed pods. The seed inside – shaped like a horse’s eye – is smooth for both trees. But a buckeye tree also has a smooth seed pod, while the horse chestnut seed pod is spiky.
But don’t confuse the spiky pods with the American chestnut, the seeds of which you can roast on an open fire, like the song. Horse chestnut seeds are toxic for people, Stavish said.
Varun Ravindran signed up for the walk and got a lot out of it.
“I’ve always wanted to identify trees and these visceral identification marks were what I was looking for,” Ravindran said. “It just makes you feel closer to trees. It’s like identifying another person – 'Oh, I see you.'"
In all, Stavish showed the group about 20 different tree species, including ginkgo, eastern white pine, and umbrella magnolia.
“It’s nice to go out and learn what some of them are,” Stavish said, “So that we can become familiar and sort of have that sense of place as to what’s around us – or maybe what’s not around us if we don’t have a lot of trees.”
This story is part of the Allegheny Front series Wild Pennsylvania.
