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Plant Focus

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First described by the Japanese botanist Bunzō Hayata in 1913, Quercus hypophaea is a medium to large evergreen oak restricted to the...

Burr Oak Canyon Symposium 2019

On October 17, 2019, 80 participants gathered in McCook, Nebraska for a two-day conference and field trip titled “Growing Better Trees Across the Great Plains”. The event was sponsored by the Norris Institute, Nebraska Statewide Arboretum, Nebraska Forest Service, Mid-Plains Community College, and others. Uniquely arranged, the Nebraska Statewide Arboretum (NSA) has small, satellite collections throughout the state, designed to generate interest and demonstrate what grows best in each region. NSA also propagates and sells native plants.

Group
Group photo at Burr Oak Canyon

Thursday morning began with workshops and lectures and ended with a tree planting in the nearby park. The evening festivities included a barbecue IOS member Bruce Hoffman’s nursery, Common Scents. Bruce did a tremendous job (along with several others) organizing and planning this event.

From the lectures, here are a few highlights that might be interesting to the IOS membership:

Greg Morgenson, Woody Plants Specialist at North Dakota State University, explained that Quercus alba and Q. bicolor can be grown in North Dakota if they are grafted on Q. macrocarpa rootstock. He showed photos of fossils illustrating that Ginkgo biloba and Cercidiphyllum japonicum were once native in the state.

IOS Member Tim Buchanan, retired City Forester of Fort Collins, Colo., presented photos and a list of oak species generally recommended for his area.

  • Section Quercus: Q. macrocarpa, Q. muehlenbergii, Q. prinoides, Q. turbinella, Q. ×undulata, Q. gambelii.
  • Section Lobatae: Q. shumardii, Q. buckleyi.

Tim mentioned that many other species are currently under evaluation. Surprisingly, one 15-year-old Q. nigra has performed very well and survived -20 °F. Also of note, a seed selection of Q. buckleyi known as “Collins” is grown from seed of the best Q. buckleyi in Fort Collins, and this mother tree was grown from wild-collected seed from the Lubbock, Tex. area. The forester from Cheyenne, Wyo. recommends the hybrids Q. macrocarpa × robur and Q. macrocarpa × turbinella.

Brian Byers, co-owner of Great Plains Nursery, described how they grow their woodies in RootTrapper® grow bags and RootMaker® air-pruning containers, so the plants grow numerous fibrous roots and few circling roots. They are growing and selling the “relict bur oak” from Burr Oak Canyon and “Collins” Q. buckleyi. He noted the Q. macrocarpa from the Black Hills of South Dakota tend to be plagued with galls, even when they are grown in Nebraska.

Eric North, University of Nebraska–Lincoln, gave us the following tree statistics: there are an estimated 3 trillion trees on the planet; 60,000 species; 750–1,000 species north of Mexico; and about 50 species in Nebraska. The United States has both the oldest (Pinus aristata, 4,900 years) and tallest (Sequoia sempervirens) known trees.

Tim McDonnell of the Kansas Forest Service provided a list and photos of his tree recommendations for a diverse and sustainable landscape. Diversification to him means having 15% or less of one family, 10% or less of one genus, and 5% or less of one species. He has ventured into recommending non-natives that are well behaved. For example, there is a planted male Pistacia chinensis in Manhattan, Kan. that survived -25 °F. Tim mentions that they have many trees under evaluation currently. He told me that Q. laceyi is being grown as far north as Kansas City, Mo. and encouraged me to try it another 100 miles north. Someone have seed to share :o)? 

Canyon
Grove of oaks at the canyon

Friday afternoon we traveled to the area known as Burr Oak Canyon. This area is privately owned by cattle ranchers Roger and Lisa Lewis who graciously granted access to this location on their 3,900 acres. Both Roger and Lisa attended the barbecue, and Roger joined us in the canyon. Great people!

Once inside the canyon, Tim Buchanan, Bruce Hoffman, and Steve Rolfsmeier (Chadron State College botanist) swung into action and made sur,e we understood what we were seeing.

Canyon 2
"Tree talk" under a mysterious oak

A number of questions come to mind when exploring this canyon, such as why does this isolated population of oak trees exist? One reason may be introgression, and we saw potential evidence of genetics from Q. gambelii and Q. stellata along with the Q. macrocarpa. One individual looked like mostly pure Q. gambelii, complete with small unfringed cups.  

Cups
Gambel-like cupules on one individual

There was great variation in form and leaf. Overall, the twigs are thicker and the branches more descending than the “average” Q. macrocarpa form. The consensus was this was due to both environment and genetics. I do not recall seeing any trees that grew above the top of the canyon. This is an area of high wind and annual precipitation that averages 14 in, with occasional flash floods. Several individuals had exposed roots that had grown bark—and one of these roots had grown a twig with a leaf! 

Mature tree
Eleven-foot circumference on an old oak

Efforts are underway to help these trees. There was not a good mix of oak tree sizes as most were old, mature trees. The owners are taking steps to exclude their cattle. Several relict oak seedlings have been planted inside cages to exclude deer (a.k.a. pasture rats). At least two parties are collecting seed and growing seedlings to be planted in the canyon and elsewhere. Juniperus virginiana was present, but not in large numbers. No birds or squirrels were seen, although Roger noted he hunted squirrels when he was younger. There were few acorns this year, and Bruce and the critters had already removed them.

Leaves
Interesting leaf variation on specimens found in Burr Oak Canyon

Thanks again to the ranch owners Roger and Lisa Lewis. I was encouraged by their appreciation for these trees, as well as the number of younger participants at the Symposium.

Leaves 2
Quercus macrocarpa taking on fall coloring in Burr Oak Canyon

Photos © Dan Kostka