As member of the white oak group, Q. macrocarpa has characteristic round-lobed, unbristled leaves.  They are a leathery dark green in summer, 6 to 12 inches long with many lobes, the middle one usually especially deep, visually dividing the leaf into two parts.   Autumn color is usually gold to golden-brown.  As mentioned above, the ashy-grey to brown bark is exceptionally thick and scaly, developing deep vertical grooves as the tree ages.  As an oak, male and female flowers are borne separately on the same tree, the male in the form of greenish-yellow catkins and the female as small green and red spikes; both are aesthetically insignificant and emerge with the leaves in spring.  Q. macrocarpa exhibits a very strong masting behavior in acorn production, where acorns are sparsely produced in most years, with a very heavy crop every four to ten years.   This is believed to be an evolutionary adaptation to overcome the heavy feeding of wildlife on acorns (reducing the wildlife population in light acorn production years) and a low germination rate; typically only 0.01% to 0.1% of acorns produce a viable tree in the wild.  The acorns are the largest of any North American native oak and are enclosed in a deep, burry cup that often attracts moss spores due to moisture retention.   The Latin specific name macrocarpa ’literally translates as ‘big seed’.

In habit, the bur oak is among the faster-growing oaks, with a typical rate of one to two feet per year when young with an oval crown.   As the tree matures, it becomes more massive, with a crown broader than tall and anchored by many relatively low, thick branches.   Although tolerant of some light shade, the species strongly prefers an open, sunny situation.  As an oak, it is susceptible to several pests, including galls and gypsy moth damage, but the species appears to be more tolerant of two often-fatal fungal diseases, sudden oak death (SOD) and oak wilt than the more vulnerable red oak group.  The wood, like most oaks, is hard and durable, and is used most frequently today for flooring and cabinetry, but historically was a preferred lumber for wagon wheels and tongues, ox yokes, and barrels due to its strength.   The acorns are a favorite food of several native species, including wood ducks, wild turkeys, white-tailed deer, rabbits, mice, squirrels, and black bears.

For the landscape, Q. macrocarpa is a valuable tree for more open properties and large lawns, where it has sufficient room to mature to its broad and beuatiful form.  WHN supplies bur oak in 2”, 2½” and 3”caliper.  It’s definitely not for every landscape, but where it has the room to grow, it can be a spectacular native specimen.