By Len Phillips, ASLA Emeritus
Chinkapin oak was selected as the Society of Municipal Arborists (SMA) Urban Tree of the Year in 2008 by the SMA. Chinkapin or Chestnut oak is native to eastern North America, from Vermont and southern Ontario west to Iowa, south to northwest Florida and eastern Texas, with isolated populations in west Texas, southeast New Mexico, and eastern Mexico from Coahuila south to Hidalgo. It is occasionally seen outside its native range with groves in Ottawa, Ontario, Raleigh, North Carolina, and Lake Worth, Florida.
The name “Chinkapin” comes from the resemblance of the leaves to those of a chestnut or chinkapin. This tree has the botanical name of Quercus muehlenbergii which is pronounced KWERK-us mew-len-BER-jee-eye. The tree is in the Fagaceae or Beech family. The Chinkapin oak is also sometimes called yellow chestnut oak, rock oak or yellow oak.
The wood of the Chinkapin oak is a durable hardwood, prized for many types of construction. Early pioneers used its straight wood to make thousands of miles of fences in the states of Ohio, Kentucky and Indiana. Later on, the trees were used to fuel the steamships that ran from Pittsburgh to New Orleans. It was also used as railroad ties for the new railroads that crisscrossed the Midwest in the mid to late 1800s.
Mature Chinkapin oaks can have a height of 40 to 60 feet and a spread of 50 to 60 feet in landscape conditions, but up to 30 feet larger in the wild. It will attain a rounded shape with a crown that appears irregular in outline or silhouette. The tree does have blooms that are insignificant and brown in color from May to early June. The flowers will produce one-inch-long acorns about 6 months after pollination. The Chinkapin oak is especially known for its sweet acorns. Chinkapin acorns are at the top of the food preference list for wild turkeys, grouse, whitetail deer, black bears, chipmunks, squirrels, and hogs. Cattle will eat the leaves.
Chinkapin oaks have yellowish-green leaves in the summer. They turn yellowish-orange to brown in the fall. The tree has no special winter interest except the ashy light-gray bark that breaks into narrow, thin flakes.
The tree grows in the wild on well-drained bottom land soils and limestone hills near water, but it is adaptable to a wide range of soils and exposures. It tolerates wet sites, but does best in well-drained areas that do not experience severe drought. The Chinkapin oak handles alkalinity very well. This is an oak that has been planted often in the central part of the country where soils are claylike and alkaline. It will grow quite nicely in other areas of the country as well. This oak does well in full sun. The tree survives in USDA Hardiness Zone 3 through 9A. The growth rate is moderate when the tree is young but it slows considerably with age. It develops the open rounded crown as it ages.
Chinkapin oaks experience no pests or diseases of major concern. They are resistant to breakage during storms. However they are only moderately resistant to road salt spray and have a poor tolerance to salt in the soil. The tree has no proven urban tolerance. Chinkapin oaks are propagated by acorns but are considered difficult to transplant after germination. As a result, the tree is only somewhat available, so purchases may require going out of the region to find the tree in a nursery.
The branches droop as the tree grows and will require pruning for vehicular or pedestrian clearance beneath the canopy. However, the tree needs very little pruning to develop a strong structure. Chinkapin oaks are worthy specimens for larger lawns, estates, or parks. They are also useful for large parking lot islands with more than 200 square feet in size and wide tree lawns more than 6 feet wide. They are not particularly showy and should be grown with a single leader. They are recommended for buffer strips around parking lots or for median strip plantings in the highway. They are useful as a reclamation plant. This oak should be grown with a single trunk and widely spaced branches to mimic its growth habit in the wild.
As it matures, Chinkapin oak becomes a magnificent specimen and a conversation piece.
The Society of Municipal Arborists conducts an Urban Tree of the Year competition to illustrate the importance of selecting the right tree for a planting site. The intent of this annual selection process is not to indicate that this tree is the perfect tree that can grow anywhere, but is to make municipal arborists aware of this tree and they should use it if they have a site suitable for it. The Urban Tree of the Year competition also provides extra publicity for excellent trees that should be used more often. Too often our cities contain common maples and ash that are cheap, easy to grow, and are short-lived. A quality urban tree is better over the long- term. Cities last forever, why plant a tree that will live less than 20 years. Runner-up in this year’s competition was the Princeton American Elm.
* Gilman, Edward F. and Dennis G. Watson, “Quercus muehlenbergii,” USDA Forest Service, Fact Sheet ST-552, October 1994.
* National Arbor Day Foundation, “Oak, Chinkapin”, Tree Guides, 2008
Len Phillips can be reached via e-mail at firstname.lastname@example.org