The Mighty Oak

In this August’s issue of The Advocator, I write about oaks. Here is a companion piece to that article. I’m sending you on a scavenger hunt of sorts.

Note well: Inman Park is fortunate to have easy access to a remarkable collection of oak species and varieties along the Eastside BeltLine, planted there by Trees Atlanta of course, as well as a striking installation of oak-leaf sculptures by artist David Landis.

“33 Oaks” by David Landis, commissioned by Trees Atlanta

White oak (Quercus alba)

The monarch of our urban forest! Look for leaves with 7-9 rounded lobes and bark that is silvery or light-gray and grows in flat scales or plates, as you may be able to see on the upper branches of this white oak at 100 Waverly Way (click for larger image):

White oak (Quercus alba)

Or visit this triumvirate of younger white oaks within the oval of Poplar Circle. Planted in the same year and in the same location, they have nonetheless shown remarkable variability, as you can judge for yourself by looking at their fall colors:

White oaks (Quercus alba), playground behind

Fact: There’s a white oak at the Bitsy Grant Tennis Center that is 142 feet tall, and another one in southwest Atlanta that is 18 feet in circumference at 4.5 feet off the ground.

Swamp white oak (Quercus bicolor)

The leaves of the swamp white oak look like wavelets in the ocean. You can find this tree on the north side of Euclid Avenue at the Hurt Mansion (granite marker at its base).

Fact: Swamp white oak is the species chosen for the plaza at the September 11 Memorial in Lower Manhattan. Interestingly, sweetgum (Liquidambar styraciflua) was also to be planted, presumably a fruitless variety, but in the end their blazing red fall color became an issue. The architect Michael Arad said, “I felt the design — reduced to its most essential elements — was the twin voids. I really didn’t want to have anything that would distract from the clarity of that.” Watch a trailer for a documentary about the 415 oaks at the site below.

Scarlet oak (Quercus coccinea)

As the name implies, scarlet oak is in the red oak group. Its leaves have 7 pointed lobes (not rounded as in the white oak group), and each is tipped with a bristle. Take a stroll past the Floyds’ home at 116 Elizabeth Street and keep in mind we planted their tree just 15 years ago in 2006!

Fact: Henry David Thoreau wrote an entire essay about scarlet oak. It begins, “Belonging to a genus which is remarkable for the beautiful form of its leaves, I suspect that some scarlet oak leaves surpass those of all other oaks in the rich and wild beauty of their outlines.And about the fall color, he says, “[E]very leaf, between you and the sun, as if it had been dipped into a scarlet dye. The whole tree is much like a heart in form, as well as color.

Southern red oak (Quercus falcata)

I’m going to send you over to Dekalb Avenue, just west of Marble Lofts.

Southern red oak (Quercus falcata)

I’ve written about this southern red oak before. There’s another wonderful specimen at 513 Seminole Avenue (see below). Check those leaves out: the long central lobes or apexes on dark-green, glossy, leathery-looking leaves, with undersides of a tawny color, is a sure giveaway, though leaf shape especially on younger trees can be quite different (pear-shaped, tri-lobed, etc.)

Fact: The ground underneath a southern red oak is more than typically clear of undergrowth. The reason why is salicylic acid. Rain dripping from the leaves carries SA from the tree to the ground. SA then acts as a so-called phytotoxin, inhibiting the growth of other plants.

Georgia oak (Quercus georgiana)

This little guy’s home is granite outcrops — in fact, another name for it is Stone Mountain oak. In 2002, we had the crazy idea to plant these rock-loving trees along Dekalb Avenue, opposite its intersection with Hurt Street. Still there! You can also see this unusual red oak at the north end of Elizabeth Street, in the center of the junction of two BeltLine approach trails.

Fact: Georgia oak is one of two oak species native to the state listed as endangered in “The Red List of Oaks 2020,” from the Morton Arboretum and the International Union for Conservation of Nature. The other species is Oglethorpe oak (Quercus oglethorpensis). “The Red List” states that about 31% of the known 430 oak species around the world are threatened with extinction.

Overcup oak (Quercus lyrata)

Overcup oak is in the white oak group. The common name describes the acorn: the cup or cupule extends over much of the nut (see below). Why? It’s said that the corky cupule is like a life jacket for the acorn, enabling it to float in the oft-flooded wetlands where this tree is truly at home. The classic shape of this tree’s crown, rounded and open, is on beautiful display in front of the Inman Park Church — check it out on your next stroll!

Fact: So-called floodplain or bottomland species, such as overcup oak, make excellent urban trees. It has to do with soil compaction, which is all too common in cities. Compacted soil is not good for roots. If compacted soil gets wet, however, as it often does in rainy Atlanta, roots suddenly and briefly have an easier time of it. That’s when a tree which has evolved to thrive in wet soils can seize its opportunity, while an upland species such as scarlet oak or chestnut oak can’t.

Chinkapin oak (Quercus muehlenbergii)

Our chinkapin oak is right next to our swamp white oak on Euclid Avenue opposite the Pendleton Apartments, and it too is identified with a granite marker. Compare leaves on the two trees: the chinkapin’s leaf is toothed, as on a saw. They’re said to flutter like aspen leaves in the wind (n.b. I need to check this). Our chinkapin oak would prefer to growing upon on some limestone outcrop, where the soil is alkaline, but ours is nevertheless doing great here in acid-soiled Atlanta!

Chinkapin oak (Quercus muehlenbergii)

Fact: The name Q. muehlenbergii commemorates a Pennsylvania pastor, Gotthilf Heinrich Ernst Muhlenberg (1753-1815), who found specimens of this oak growing on limestone slopes along the Conestoga River near Lancaster. He saw that it was a new species. He himself wanted to call it Q. castanea, the latter term meaning “chestnut,” because of the similarity in the leaves of this oak and American chestnut. In the end, he was honored by his fellow botanists by their naming the tree for him.

Water oak (Quercus nigra)

Look for leaves shaped like a duck’s foot!

We all know these fast-growing, ubiquitous trees, which were completely shading many of our streets in 2000 when my family and I moved to Inman Park.

Water oak (Quercus nigra) in Freedom Park at Poplar Circle
Water oak (Quercus nigra), also at Poplar Circle (Euclid and Hurt intersection)
Water oak (Quercus nigra) along the Freedom Park path above Austin Avenue

Fact: We’re all really going to miss these mature water oaks in Inman Park when they’re almost entirely gone. These trees may not live long, but they supply wonderful shade while they’re around, and the critters love them — just watch your squirrels! You’re thinking, “Isn’t there a new generation of water oaks on the way, Jim?” Not so much. We don’t plant them, and water oaks that volunteer tend to get mowed down, weeded, Roundupped, and otherwise killed at the seedling stage. Here’s one exception.

Willow oak (Quercus phellos)

I’m delighted to report that, in the years since I made this video, the owners of 951 Edgewood Avenue have removed the English ivy and the cherry laurel saplings from the vicinity of this impressive willow oak.

Fact: Not every oak species produces an annual crop of acorns — willow oak does, which, if your diet happens to be acorn-heavy, is welcome, though if you’re some homeowner’s yard crew, not so much. One tidbit about Q. phellos that catches my eye: it’s not tolerant of shade, but that said, a willow oak seedling can survive for up to 30 years under a forest canopy, dying back and sprouting repeatedly as it waits for sunlight to find its way down to it through a newly opened gap in the green ceiling above it. (Nature never ceases to amaze.)

Northern red oak (Quercus rubra)

At the NE corner of Elizabeth and Waverly (213 Elizabeth), Ann and Bill Moore are the proud owners of this 15-year-old tree (photo from October 2019, so it’s even bigger now).

Northern red oak (Quercus rubra)

If you’re serious about tree identification, you need to go beyond leaf shape and the texture and color of the bark. I recall my friend, horticulturalist Steve Sanchez, showing me how to distinguish white ash (Fraxinus americana) from green ash (Fraxinus pennsylvanica) by examining leaf scars on twigs.

Still, it’s certainly true that a typical leaf of the northern red oak has a more leaf surface than several of the other oaks in the red oak group, with sinuses (that’s the term for those indentations between lobes) that are shallower, and that its bark often exhibits what the guidebooks call “ski tracks,” easy to see on the photo below:

Fact: The online Wood Database says that northern red oak is probably the most popular hardwood in the U.S. It goes on to note that the pores in this species of oak — the tree’s plumbing, as it were — are so large and open that the story goes a person can blow into one end of the wood, and air will come out the other end.

Endgrain of northern red oak, magnified 10x (from The Wood Database)

Shumark oak (Quercus shumardii)

It can often be hard to distinguish one oak from another, e.g., a white oak from an overcup oak, or a northern red oak from this tree, known as Shumard oak.

Notice that the sinuses on a Shumard leaf are deeper than those on a northern red, coming closer to the midvein. They’re also more obviously u-shaped, while northern red has sinuses that more nearly approach a v-shape. You can also see a difference in the flat green of northern red versus the glossier green of Shumard.

There was once a massive Shumard oak on the street in front of what is now the home of Karin and Jacques Mebius.

It died. I kept expecting to plant a new tree in front of their home, but instead the Mebiuses managed to grow two new Shumard oaks from acorns of the parent tree. Love it!

Post oak (Quercus stellata)

The species epithet of this tree, stellata, means “star-shaped.” presumably because of the approximately star-shaped leaves, though it’s more commonly said that the leaf is cross-shaped. In any case, the leaf makes the tree relatively easy to identify:

Post oak (Quercus stellata)

You can find one post oak where Ashland Avenue dead-ends after crossing Hale Street. Another is in the yard at 61 Waverly Way. Notice how the branches may be twisted and gnarled in this species of oak:

Fact: To my knowledge, there aren’t many post oaks in Inman Park, compared to other oak species. You might then wonder: how will the few that we have reproduce? It’s a good question. On the one hand, oaks are monoecious, i.e, every oak has both male and female flowers. Maybe each tree can reproduce itself? On the other hand, oaks are “relatively self-incompatible.” They have developed mechanisms to limit inbreeding. So where does that leave our post oaks? Is there a botanist in the house?

Live oak (Quercus virginiana)

I have written about our live oaks in earlier posts.

Live oaks (Quercus virginiana) on Elizabeth Street
Live oak (Quercus virginiana) at the Justice Center
Live oak stump at Springvale Park

Joel Hurt, the developer of Inman Park, is thought to have been especially fond of this coastal oak species. If you have any doubt about Hurt’s hands-on approach to choosing which trees to plant in Inman Park, consider this. It’s part of a report written by John Charles Olmsted, of the Olmsted Brothers firm, on his meetings with Hurt on May 18-19, 1902, to discuss plans for the design of Druid Hills:

“Then Mr. Hurt talked about planting matters in which he takes a special interest, having planted Inman Park and his own place and some other private places. . . . He talked steadily and rapidly until 6.45 P.M. mainly about plants and put off half a dozen people who telephoned him. I borrowed the list of nursery stock to correct and copy alphabetically, giving quantities, separating trees, shrubs, vines and herbaceous and adding for his benefit the local southern common names.”

Fact: We say that live oak is evergreen. In fact, it doesp drop its leaves. This happens in late winter, just before the new leaves emerge.

There are other oaks in Inman Park, not listed before: Nuttall oak (Quercus texana), cherrybark oak possibly (Quercus pagoda), pin oak (Quercus palustris), and perhaps more.

What would we do without them? Let’s don’t find out. Plant an oak and keep our city cooler, cleaner, and more beautiful.

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