Team Tree Blog

Tree of the Week: Beacon Oak (Quercus bicolor ‘Bonnie and Mike’)

by Andrea Fick

We are all familiar with the phrase “strong as an oak”.  It’s used when describing an object or person that is capable of withstanding tremendous physical stress.  The phrase is just one example of how the oak tree has influenced people throughout history.  People have used the tree as a religious and political symbol, as well as attaching historical importance to individual oak trees.  The oak species also produces high quality lumber that is desired for its beauty as well as durability.

This week’s tree of the week is the Quercus bicolor ‘Bonnie and Mike’.  The common name for the tree is the Beacon Swamp White Oak.  It was discovered in 2007 by Michael and Bonnie Dirr during one of their excursions to Virginia.  The thing that attracted them to this particular tree was its fastigiate growth pattern.  The upward branch growth set it aside from the other larger spreading oaks in the area.  By 2009, a California company was ready to cultivate the species in their fields.

oak leaves

Photo Courtesy of J. Frank Schmidt and Sons Co.

Beacon Oak

Photo Courtesy of J. Frank Schmidt and Sons Co.


This species has the same growth range as the common swamp white oak and grows from the Midwest to the East, but can spread as far South as Tennessee and Virginia.  It is classified as a hardiness zone 4 tree.  The tree grows best in full sun, but can tolerate shade.  The growth rate begins slow, but gradually increases to a moderate rate, averaging roughly 30’ in 30 years.  The overall height can range from 30’-35’ and its spread can range from 12’-16’.

With branches growing upright and tight to the trunk, the tree can be utilized in several locations including boulevards, residential lawns, parks and gardens.  They survive well in boulevards due to their history of growing in adverse conditions found in swamps and lowlands, where they are exposed to extreme flooding and droughts.  The species can handle exposure to salt commonly found along thoroughways, boulevards and sidewalks.  It doesn’t have many issues with insects or diseases, and it is more resilient to oak wilt because it is a white oak.

The characteristics of this species are similar to the common swamp white oak.  The leaves are alternate, simple, and obovate and range from 3”-7” long.  The teeth around the margin are irregular and add a nice aesthetic appeal to the leaf.  The leaves are a shiny, dark green in the spring and summer and change into a nice golden yellow in the fall.  This fall color can really accentuate the tree in the landscape.  It is a monoecious plant and contains both male and female flowers.  The yellow-green male catkins are more noticeable than the smaller red female flowers found in the leaf axils and can add to the aesthetics of the tree.   Acorns produced by the tree are roughly 1” long and are a nice tan color.  Acorns can attract wildlife which contributes to the biological diversity of the landscape.  The bark of the young twigs is smooth and light-brown in color, while the older, mature bark is a light gray and is furrowed with irregular fissures.


  1. JFS Introductions, Quercus bicolor ‘Bonnie and Mike’ Beacon Oak [Online Image]. (2015). Boring, OR.  J. Frank Schmidt and Sons Co. Retrieved from
  2. Blooming & Beautiful. Beacon Swamp White Oak. (2011). Retrieved From.
  3. Virginia Tech University. swamp white oak, Fagacea Quercus bicolor, Willd. (2015). Retrieved From.
  4. Penn State Extension. Home Lawn and Garden, an Interview with Michael Dirr. (2015). Retrieved From.
  5. Gibney, Richard W. Cultivars of Three North American Trees. web. 02 December 2015.


Tree of the Week: Highland Park Maple (Acer grandidentatum x saccharum ‘Hipzam’)

by Nick Perry

When you see or hear the word autumn, what is the first image you have? Many people immediately think of the spectacular color changes in the foliage. The magnificent reds, yellows and oranges can really be prominent during sunny autumn days.

This week’s “Tree of the Week” does not disappoint when it comes to displaying brilliant fall coloring.

The Highland Park Maple, Acer grandidentatum x saccharum ‘Hipzam’, is part of the Sugar Maple family and is native to North America. It is classified as a Zone 4 tree on the USDA hardiness map and can be grown in the majority of Minnesota.

The Highland Park Maple is not a very large tree in size. It can grow between 30 and 50 feet in height and its spread can vary from 20 to 25 feet. With a pyramidal growth habit, it can be used in both group plantings or as a stand-alone accent tree in a residential yard. It requires full sunlight and grows at a medium rate. Because it can handle adverse growing conditions, this maple may be able to grow where other similar maples do not fare as well. The capability to tolerate dry soils and urban pollution allows it to grow in commercial and residential environments. The ability to resist pests and diseases also add to its allure. It shouldn’t be considered for boulevard plantings, as it does not fare well in saline soils and its lateral branches typically arise roughly 7­8 feet off the ground.

The tree does not produce any showy flowers or fruit. It does, however, have very nice foliage. The leaves are sturdy and tatter­proof. In the spring and summer, they are a rich dark green. In the fall, they begin to change color producing gorgeous reds, yellows and oranges.

Young, red branches also add an attractive element to the landscape throughout the year. The red branches can really look picturesque against the freshly fallen snow.

The University of Minnesota has successfully grown the Highland Park Maple species at their St. Paul field location. They will provide several of these specimens to local areas including the City of St. Paul and the Minneapolis Park and Recreation Board.

Highland Park Maple

Photo Courtesy of Willoway Nurseries, Inc.

Willoway Nurseries Inc. Acer grandidentatum ‘Hipazam’ – Highland Park Maple. 2015. Willoway Nurseries inc. Avon, OH. Willoway Marketing. Web. 23 October, 2015.


Plant Finder: Highland Park Bigtooth Maple. (n.d.). Chalet Nursery website. Retrieved from

The Tree Farm: Highland Park Bigtooth Maple. (2010). The Tree Farm website. Retrieved from

Acer grandidentata. ‘Highland Park’ Bigtooth Maple. (n.d.). Robinson Nursery website. Retrieved from­content/uploads/2012/02/Acer­grand.­Highland­Park.pdf

As Tough As Nails. (2010). Lake County Nursery website. Retrieved from­room­pr­Elaeagnus­Titan­Acer­Highland­Park.html

Tree of the Week: Osage Orange (Maclura pomifera)

by Andrea Fick
Osage OrangeThis week’s tree is the Osage orange (Maclura pomifera). This small deciduous tree grows best in full sunlight and can reach heights of about 30 to 40 feet tall. It has a short trunk and outward branches that form a low, dense rounded crown. Young twigs have green bark while older bark is orange-brown with deep furrows. Twigs of this tree are often thorny, but there are thornless varieties. Due to its natural form, Osage orange is often used as a hedge plant. It was used as a living fence before the invention of barbed wire.
Osage Orange hedge ballsOsage orange is part of the Moraceae, or mulberry family. It is dioecious, meaning there are male and female trees. Female trees produce a green, bumpy fruit resembling the size and shape of an orange. The fruit are referred to as hedge balls or Osage orange balls. Squirrels like to eat the fruit of the Osage orange. The fruit is also sold as a way to repel insects, however there are debates as to whether it is effective or not.  Osage orange also goes by various other names including hedge-apple, horse apple, and bodock.


We currently have some young Osage Orange trees growing in the nursery. These trees came from hedge balls picked from trees located along an old fence line separating two beef cattle pastures near Pleasantville, Iowa. We expect to get more seedlings in from this source. Osage orange grows in USDA Hardiness Zones 4 through 9 and can adapt to various soil conditions.


Disease-Resistant Elms in Minnesota: The Search Continues

by Daniell Ringle

The story of planting American elm trees has become much more complicated since Dutch elm disease (DED) arrived in Minnesota. Prior to the arrival of the disease, elm saplings were often dug up from the wild and transplanted into cities and communities. Now we have to go through a rigorous process to find disease resistant elm cultivars, because anything we plant from the wild has a high likelihood of becoming infected with DED. There are some disease-tolerant elm cultivars being planted in Minnesota, but they are not from the state (Ed. As of this writing, the St. Croix™ Ameican elm did not have wide commercial availability. St. Croix™ is the first disease-resistant American elm selected from a Minnesota-native parent tree. It is currently being produced and marketed by Bailey Nurseries and is now available in retail and wholesale nursery and garden center outlets.) Team Tree is trying to find resistant elm trees in each quadrant of the state so that we can have Minnesota grown cultivars adapted to our unique climate. We are specifically looking for mature elms that have lived since DED was found in Minneapolis in the 1960’s and likely have natural resistance to the disease. After identifying a specific mature elm that we would like to replicate, we collect fast growing branch tissue during the winter dormancy period.

collecting elm cuttings

Collecting elm cuttings in Mankato, MN

scion material

Branch material for experimentation

When we are ready to use the dormant branch material, last year’s new growth is grafted or processed as stem cuttings to make a clone genetically identical to the tree it came from. To make a rooted cutting, we cut a section of branch material several inches in length and plant it in a rooting medium. To encourage root establishment, we dip the cutting in a concentrated hormone solution that originates from a growth regulator that plants produce to initiate the growth of new roots.

Rooting cuttings (of cottonwood, not elm)

Rooting cuttings (of cottonwood, not elm)

Modified cleft grafting, however, is best cloning technique if we want quick growth, because the tree can allocate all its energy into one small grafted branch, instead of having to focus on developing new roots. When grafting, a wild elm seedling (rootstock) is used for the base of the new tree and a few inches of potentially resistant branch material (scion) is grafted to it. We do not allow the rootstock material to form leaves and branches, so the resulting tree will be completely from the scion wood. The purpose of the rootstock, as you could likely guess from its name, is solely to be the root system of the tree.

Grafted elm clone

Grafted elm clone

Successfully leafed out elm in its first season post-graft

Successfully leafed out elm in its first season post-graft

Mature, disease resistant elm

Mature, disease resistant elm


Because we usually graft in the wintertime, we keep the newly grafted trees in a greenhouse so they have a head start on the growing season. We then move them out to our nursery for the summer. From this time until the tree reaches 3 to 5 years of age, the main focus is on growing a large healthy clone. Once the tree is large enough, it is inoculated with Dutch elm disease to test for resistance. Any trees that have shown that they can survive exposure to DED after several rounds of testing will be used for restoring American, red and rock elm to Minnesota’s landscape. We hope that someday the fruits of our labor will pay off and result in a specimen such as the one posted above.

Team Tree

Team Tree in SW Minnesota

Team Tree

Team Tree in Lake City, MN

American Elm Forms and C.C. Laney in 1908

by Chad Giblin

American ElmsOne hundred years ago, well before Dutch elm disease (DED) made its way to our shores, we had the time to ponder the many wonderful qualities of America’s favorite shade tree, the American elm (Ulmus americana). In April 1908, C.C. Laney published this wonderful article in The Garden Magazine:

“The Types of the American Elm” (.pdf)

One might dismiss this article as just a bit of horticultural antiquity, but there is much to be learned from it. These elm forms can still be found on the streets and in the parks throughout America. Look around and you’ll likely see a “willow-type” or “pitcher-type” elm. In the Twin Cities area we’re apparently quite lucky to have many of the reportedly “rare oak-type” American elms.

Take a few moments out of your busy day and travel back in time when we could encourage our children to:

“know [these elms] by name … to make pilgrimages to them, to hold picnics and little parties under them. And so a love for the trees would be cultivated by association and the next generation, being friends to the trees, there would be no need of enacting laws to compel their preservation.”  – C.C. Laney, 1908