OK, I’ve presented two of my favorite trees, northern catalpa and ginkgo, and today we get to finish my favorite tree trifecta with bur oaks. Like the first two they’re very different trees and the bur oak is different from them as well.
Although there is some speculation on native range distributions, by most accounts burs oaks, historically referred to as the “mossy-cup” oak, is the only native oak to South Dakota. There is a mention of white oaks in the Black Hills in an 1895 publication and other sources claim swamp white and northern red oaks are also state natives but solid documentation on that is hard to find.
The bur oak is a species within the white oak section of the genus Quercus. They can get quite big and quite old. Individuals over 400 years old are reported as are ones over 150 feet in height. In central South Dakota a bur getting over 60’ tall would be extremely noteworthy for several reasons, weather for one and European homesteading and timber harvest for another. I learned to identify bur oak leaves in undergrad by their outline resembling ice cream cones; ice cream is cold which makes one go “brr” which then leads to “Bur”, and 11 years of college later here we are. They do have the largest acorns of the oaks hence their species name, macrocarpa, which comes from ancient Greek makros meaning “large” and karpos meaning “fruit.” Go figure science making sense!
Burs tend to produce acorns heavily only every few years, something called “masting” which overwhelms the many acorn eaters allowing a good chance of at least some of the acorns to escape being eaten allowing them to germinate and carrying on the lineage. Their bark has a very distinctive cork-like patterning to it which becomes very thick with age. The thick bark actually allows the tree to be fire tolerant, which allows them to exist in fire-common areas whereas without the fires other trees would out-compete burs eventually causing them to rot and eventually die.
Burs are typically thought of as slow growing so a lot of home landscapers tend to shy away from planting them and this is too bad. First of all, any tree planted today is generally not for you but for the next generation to enjoy, so if it takes 25 years for a tree to become big, hey, that’s about right! But second, although they are slower growing than some shade producing trees, much like ginkgos they grow faster than most think as once established a bur oak can grow 2-3 feet each year.
Burs adapt to many soil conditions including our clay and alkaline soils but also do well in sandy soils due to their very large tap roots, are more cold and drought tolerant than most species, and do not drop branches unless they are in shady conditions. Bur oaks make my top three list because of their unique bark texture, their longevity and eventual size, their poor soils and cold tolerance, and well, because they’re an oak! A native tree well suited for our area, a soild performer, bur oaks are well worth adding to your urban landscape.
Art Smith is a co-owner of East Pierre Landscape and Garden Center, 5400 SD Hwy 34, Pierre