The United States of America is a unique, goofy place and Fourth of July seems to bring about a universal patriotic mood – especially in our Nation’s Capital! While eagles typically come to mind as the symbol of the States, did you know the U.S. has an official national tree? Only formally recognized in 2004 (!) Congress named the Oak tree as our national tree. No species, just the genus Quercus. To celebrating this stately tree, and our beloved country, we’re spending the month of July highlight Oak species prevalent in D.C. Next up is the Pin Oak, the second most common of street tree oaks!
The stately and towering Quercus palustrus is known as the pin oak. Perhaps one of the most abundant oaks in the United States, the pin oak can be found in almost all corners of the lower 48 states and has even adapted well to its introduction in Australia and is now common there as well. Illustrative of its large range is the pin oak’s versatility: it is used by hundreds of local and city governments as canopy cover in public places such as parks, public buildings, and along streets and boulevards. In D.C. is it is the second most commonly planted street tree and an excellent addition to a home (we can help you plant one for free!).
One of the characteristics that make the pin oak the tree of choice for these uses is its distinctive growth habit and handsome shape. The pin oak grows in an attractive pyramidal form with a straight and dominant trunk that firmly anchors the tree. The lower branches sweep out wide and droop slightly while the upper branches go from a horizontal to an upright angle as they reach the top.
Although the possible planting zones for the pin oak are large and varied, it is a picky tree when it comes to soil type. Quercus palustris requires acidic, moist soil and cannot tolerate a pH level of 7 or above. Nevertheless, it is tolerant of compacted soil and urban conditions. The pin oak can even adapt to flooding conditions by developing a fibrous and very shallow root system.
Growing to a height of 60 to 70 feet, the pin oak is a medium-sized tree and has broad, lobed leaves. The leaves have deep sinuses and contain 5 to 7 lobes that typically have 3 to 4 bristles extending from the tip. In autumn, the leaves can turn anywhere from a bronze to a rustic red color. The bark is fairly smooth and tight, developing small fissures as the tree ages. The pin oak’s acorns are smaller than most other oaks and are topped by a thin cap and the flowers are small inconspicuous spheres extending from the branches.
Historic uses of the pin oak include examples of the use of its bark in an intestinal remedy concocted by Native Americans and its name is said to have been derived from the early use of its wood as ‘pins’ during the colonial and frontier age that would hold the frames of buildings and structures together.
By far the most important condition affecting the pin oak is the onset of Chlorosis that comes from being improperly planted in soils that are too alkaline for the tree to transport enough iron from its roots to the upper structure of the tree, resulting in sickly white leaves that cannot photosynthesize properly. Otherwise, this species has no particular diseases or pests that are not common to other species of oaks.
As the pin oaks are so popular and widely planted, in many cases it takes no more than a walk around the block to find an example of this hard-working and picturesque tree in your neighborhood! Be sure to look for the bristles on the tips of the leaves or the thin caps on the acorns and you have found a magnificent example of Quercus palustris.
Editor’s note: We originally posted this Pin Oak profile in 2012 as part of our Tree of the Month series.