Tree Expeditions: Oklahoma

Our Senior Adviser, Mike Hayman, has over the past 30 years cultivated a tree network which now stretches from Dr. Michael Dirr, retired professor at the University of Georgia, the most influential tree man in the United States; to Richard Olsen, Director, National Arboretum in Washington D.C.; to Keith Warren at J. Frank Schmidt Nursery in Oregon, the largest and most innovative wholesale nursery in the United States.  All of them have passed on trees to Mike that have broadened the tree palate here in Louisville. Read on to learn about Mike’s latest expedition!


I traveled to visit the Clinton, OK plantsman Steve Bieberich from May 28-30. I have known Steve for 30 years after finding him via the late JC Raulston’s plant acquisition and source list at North Carolina State Arboretum (now Raulston Arboretum). Steve and a small group of plantsmen from Nebraska conducted exotic plant-finding trips to China, Mongolia, and Tibet.

Steve’s real usefulness for us in Louisville is not his Asian trips, but his testing of trees that can grow successfully in heat, dryness, and sudden temperature changes — the conditions of western Oklahoma. Those are the trees that should survive our most severe urban conditions in Louisville. While it would be better to fix the soil in those severe Louisville sites so we would have more tree choices, it would be expensive and impractical. A more sensible solution is to find trees that will do well in severe sites and plant them without expensive soil amending.

  Steve Bieberich with native shrub oak

Steve has tested Elms for the National Arboretum for decades. Elms and their relatives such as Zelkovas and hackberries are among the best survivors in poor, scarce soil in the heat island. Thirty years ago, Steve gave me a Texas Cedar elm, Ulmus crassifolia, first grown at Hidden Hill (Bob Hill), now growing at Whitehall. That species grows in a range of conditions, from drought in Oklahoma and Texas to wet soil at Whitehall. The young stems are very corky with wings that look like our native winged elm. Steve quotes the late Frank Santamour from the National Arboretum who opined that the cedar elm likely would not get Dutch Elm Disease. It is time to test that species here on a wider scale.

By chance, I acquired a dozen rooted clones of Whitehall’s cedar elm from Roy Klehm in Chicago this spring. Roy propagated Whitehall’s tree three years ago. Those young trees will be distributed locally to get more reliable local information about the cedar elm. This fall, Steve will acquire more cedar elm seed from Brazo’s Rim, Texas, a source for dense good looking seedlings. We will get some of those seedlings to test with our local wholesale growers.

The effort to bring back the American elm from near extinction caused by Dutch Elm Disease has been imperfect. The disease resistant, vase-shaped elms selected from Eastern US have tight branching that traps bark between the branches and trunk, a weak structure which leads to large branches splitting off.

Steve noticed that the prairie form American elms grew much broader than the eastern forms. These prairie forms have stronger structure and should live longer. When Steve brought this observation up, I knew exactly what he meant because I grew up in Nebraska and climbed my neighbor’s broadly branched elms as a boy. TreesLouisville will acquire ‘Prairie Expedition’ American elm, a South Dakota disease resistant American elm, from J Frank Schmidt possibly as early as this winter.

One of the toughest trees in existence is the osage orange. The massive osage orange tree at Fort Harod, Kentucky, fell over decades ago but just kept on growing. Children love to sprawl over its horizontal trunk which lays flat in the ground. All the while, the tree continues to thrive. There is a similar osage at the entrance to Oxmoor Farm.

The osage he never been popular because females produce a large useless (to us) fruit that looks like a small brain. That fruit is heavy and can be a nuisance. Also, both male and female osage have thorns. Thirty years ago Steve introduced an osage orange without fruit or thorns called ‘White Shield.’ Just now that clone has become commercially available. But like so many first introductions, it has some problems. White Shield is a rampant grower which makes it difficult to shape. Also, it does not have the bright orange bark displayed by the best osage forms.

So Steve and I have agreed to search our additional male (non fruiting) forms with better colored bark. This is possibly a long process but the result will be a canopy tree that can grow anywhere and at the same time have attractive architectural shape and bright orange bark. And if it has a few small thorns, all the better to keep the vandals off on school playgrounds.

Dr. Michael Dirr from the University of Georgia found a blue leaf Lacey Oak, Quercus lacyi, on the Georgia campus. Coincidentally, Steve has two Lacey Oaks from which he will germinate small seedlings to serve as understock for the blue leaf form Dirr found. We will test that tree in Louisville.

Other trees that we will acquire from Steve over a period of years:
-High pH tolerant oaks, chinkapin, shumard, and buckleyi to be delivered to us this fall when Steve drives to Louisville to attend national pigeon show at the Fairgrounds.
-Purpleblow maple #960110 with good fall color
-Chinese wingnut, Pterocarya stenoptera, a fast growing wetland tree. I have one tree from Steve that has been growing successfully in Seneca Gardens for 30 years.
-‘Ebony Green’ tree form Euonymus
-Prunus ‘Sucker Punch’ originally from Scott Skogerboe in Ft. Collins, CO

I want to make a point about how interconnected cooperating plants people are. From just this one trip to Oklahoma, we will get trees to Louisville because of Steve Bieberich, J C Raulston, Michael Dirr, J Frank Schmidt, Frank Santamour, Scott Skogerboe, Bob Hill, Roy Klehm, Whitehall, the TreesLouisville team, and more.

All of us are enriched by this network.

— Mike Hayman, Senior Adviser, TreesLouisville