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Post Oaks in the Big City

Post oak
This post oak thrives despite being squeezed between a parking lot and a sidewalk. November 2013. Takoma Park, MD.

If you live in one of Maryland’s older towns, you probably have a lot of heritage trees – native trees inherited from the forests and fields that existed before your town was built out. It’s part of what gives old towns so much character. In my home town, Takoma Park, one of the heritage trees I admire the most is the post oak (Quercus stellata).

Post oaks inspire me. I see beauty in their shiny, cruciform leaves and their tiny, striped acorns. I also admire the species’ capacity to cope with adversity.  Many of the post oaks in Takoma Park are confined to little hell strips, those narrow grassy areas between slabs of asphalt or concrete. There they must cope with soil compaction, deicing salts, copious quantities of dog urine, and the urban heat island, to name a few.

Post oaks are one of the most common trees at Soldier’s Delight Natural Area, where the serpentinite bedrock gives rise to a soil so laden with heavy metals that it’s too toxic for most plants to grow in. Perhaps tolerance of metals helps the post oak perform well at urban sites,  even sites near train tracks and in industrial parks.

Post oak leaves have a distinctive, cruciform outline.

Post oaks are planted by squirrels, not people, but I think perhaps we should give it a try. And I’m in good company on that score. No less an authority than Michael Dirr, author of the Manual of Woody Landscape Plants, has also “Developed a fondness for the species,” as he puts it, “because of the great foliage and picturesque growth habit. Trees become artistic, sculptural entities in old age.”

Fall color of post oak varies from golden to red
This post oak is located in a strip of grass between two parking lots. Just two blocks from the metro in Takoma D.C., it is safe to say this tree copes with the urban heat island effect, as well as de-icing salts, soil compaction, and invasive plants, especially the English ivy vine (green). This fall the tree put out a bumper crop of acorns which will be used by students at the Institute for Applied Agriculture as part of a plant propagation exercise. If successful, we’ll have many little post oaks to give away! Takoma D.C., October 2019.
A close-up of the English ivy in Fig. 3. The roots of this invasive vine dig into and destroy the bark of its host tree.


By Sara Tangren, Ph. D., Sr. Agent Associate, Sustainable Horticulture and Native Plants, University of Maryland Extension, Home & Garden Information Center

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