Plant of the Month - April, 2007

ARBORETUM PLANT OF THE MONTH FEATURE

by Frances K. Bickelhaupt
Co-founder of the Bickelhaupt Arboretum
Treasurer of the Board of Directors
Author of "A Private Couple Creates a Public Garden"

Quercus macrocarpa
Bur Oak

For many years, as I would hear the words "Bur Oak" I would immediately think of the favorite tree of Iowa: Quercus macrocarpa - Bur Oak. In the mid-50's, a site for our family's new home was selected "at the northeast corner of the ten acres to be shaded by two huge Bur Oaks and yet be close to S. 14th Street." As years have gone by, I have been very aware of many other places that have been so named for oaks. You find parks so named, museums, resorts, conservation centers, wineries and even towns. The finials at the entrance of the Bickelhaupt Arboretum are acorns. .

The oak tree was chosen by the 59th Iowa General Assembly as Iowa's official tree on March 13, 1961. According to the web site of the Iowa General Assembly,

"The Iowa General Assembly chose the oak because it is abundant in the state and serves as shelter, food and nesting cover for many animals and birds. It is difficult to find a tract of natural woodland in Iowa that does not have in it at least one species of oak. No other group of trees is more important to people and wildlife. Acorns, the nuts of oak trees, are a dietary staple of many animals and birds. Deer, wild turkeys, pheasants, quail, wood ducks, raccoons, squirrels, chipmunks, blue jays, nuthatches, grackles and several kinds of woodpeckers are a few of the species that depend on acorns for a significant portion of their diet."

Because a certain species of oak was not named, any species can be considered the Iowa state tree. Perhaps, because it is so widely distributed throughout the state, the Bur Oak (Quercus macrocarpa) is the species often identified as the state tree. It is the only native oak that is found in all Iowa counties. .

When all the exciting trees here in The Bickelhaupt Arboretum in Clinton, Iowa, were measured and evaluated in the 1970's by Dr. L.C. Chadwick, well-endowed tree appraiser from Columbus, Ohio, we all were surprised what a value the three existing Bur Oaks at the Bickelhaupt Arboretum carried. They were well over one hundred years old and afforded wonderful shade along some fence lines. Of course, we elected to keep them in the arboretum for a long time.

About ten years ago, one of our signature Bur Oaks, more than 160 years old, was struck by lightning. Many gatherings for weddings, classes, school outings, Bible studies and meetings were held on the wooden benches made years before to form an amphitheater in the shade of this magnificent tree. After much deliberation and consultation, the damaged tree had to be destroyed. Some of the people who had been married here asked for "slices" of this wood as souvenirs from their beautiful occasion. This tree had provided deep shade to the Wildflower Collection as started by Roy Nordine, retired plant propagator of The Morton Arboretum, first curator of our collections and original Board of Directors member of The Bickelhaupt Arboretum. The Nordine Wildflower Collection has now been moved to the south side of the arboretum, to flourish under the shade of another fine specimen of Bur Oak (see accompanying photograph). .

Quercus macrocarpa, Bur Oak, is a slow growing tree but easily lives to be a valuable tree. It is a rugged tree with thick spreading branches and irregular crown. It does not require special soil and that is one of the main reasons this tree has been growing for many years on farm property. In town, it is known to be sensitive to compaction. Because of a large taproot, it is difficult to transplant.

A new cultivar in the oak family is Quercus robur 'Attention' - Attention English Oak and found now planted on the far northeast side of the arboretum. However, it is known to not grow as tall as the Bur Oak. It will not replace the Bur Oak, but will be worth watching as it matures here in the arboretum.

As we enter our 37th year of the Bickelhaupt Arboretum, we are reminded that the Bur Oak was here long before the arboretum began and will be here for decades to come.

About the author: Frances K. Bickelhaupt is Treasurer of the Board of Directors, author of A Private Couple Creates a Public Garden and, at age 91, very active with an eye to the future for the garden she and Bob co-founded and have endowed in perpetuity.