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This year we're teaming up again with Saint Paul Parks & Recreation to add a few more flowering cherry trees at the Mannheimer Memorial in historic Como Park.

Last year, we had the great honor of taking care of the Spring Wonder flowering cherries (Prunus sargentii 'Hokkaido Normandal') prior to the planting that celebrated the 100th Anniversary of the original donation to the United States from Japan in 1912.   

I finally got our stereoscope linked up with our digital camera and thought to share some VERY close up photos from our flowering cherry collection.  Photos like this really help me appreciate the wonder of spring and how great and beautiful things are possible from such simple beginnings!

Kwanzan (Prunus serrulata 'Kwanzan')

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Yoshino (Prunus x yedoensis)
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Pink Flair (Prunus sargentii 'JFS-KW58')
Pink Flair Flowering Cherry Buds'



















Both Kwanzan and Yoshino flower cherry trees have long-standing popularity throughout the warmer regions of the USA.  With warmer winters and success with other species released for USDA Hardiness Zone 5, these are definitely worth a try in the Twin Cities.  We can't wait to see if these trees will put on a beautiful display of double pink blossoms!

Pink Flair arrived in Minnesota via a donation from J. Frank Schmit & Son nursery in Boring, OR.  It is a P. sargentii just like the Spring Wonder trees planted last year, and both have exquisite single pink blossoms.

Stay tuned for updates on the flowering cherry plantings at Mannheimer and for news on the activities planned for 2013.
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Check out this neat time-lapse video of our elm grafting process! Created by our very own J.W. Fillmore...and featuring American elm roostocks from our friends at Three Rivers Parks District Nursery.

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Last fall I had the opportunity to join Mr. Don Willeke in observing the removal of a large 'Iowa State' American elm at his neighbor's house in the Dean Park area of Minneapolis. This large tree was planted in 1978, shortly after Don grafted it onto a wild American elm seedling.  Unfortunately, the tree had developed major defects over the years (it had already been cabled and braced) and required removal for safety purposes. 

Don is a local elm aficionado and has been "speaking for the trees" since the 1970s. He has been my host on many visits to the forest of elm trees (amongst other species) in and around his Dean Park home.

'Iowa State' was discovered and screened by Prof. Sandy McNabb at Iowa State University from the late 1960s to early 1970s where it proved to be quite resistant to Dutch elm disease (DED) when inoculated with the fungus. While not widely released (at least to my knowledge) this tree remains an important reminder of those lucky escapes - native American elms with high tolerance to DED. Unfortunately, the structure of this tree is less than ideal as it has a tendency to form weak branch unions due to inclusions and very acute angles of attachment.

Like 'Iowa State', many of the trees surrounding Don's home and neighborhood are from the breeding and selection programs of Dr. Eugene Smalley and Ray Guries, Dr. Alden Townsend, and Dr. George Ware. This section of the Minneapolis urban forest is truly a testament to the tireless work of these great scientists and homage to a Golden Age of elm selection and breeding.


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In my ongoing efforts to make-lemonade-outta-lemons I worked with Don and Jay Linn from Log and Limbs Company (who was performing the removal) to collect some prime cuttings material for cloning of this now rare tree.  

By the end of the removal process Don and I were able to collect some vigorous vegetative shoots from the very top of the tree, which I brought back to the University for propagation and inclusion into our elm program.

Now, weeks later, I transplanted some of the first rooted cuttings of 'Iowa State' and can now add this tree to the growing collection of elms at the University of Minnesota.

Rooted IA State Cuttings

Plants are also slated for distribution to the USDA National Arboretum in Maryland for inclusion into their continuing work on the American elm.

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IA_StateDon and Iowa State "Cookie"
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This December Jonathon and I (Greg) trekked out around Minneapolis collecting cuttings for asexual propagation for the Heritage project and came across this champion black willow (Salix nigra). Willow is considered to be a short lived tree that is prone to decay and failure because it grows too quickly for its own good. That is a good thing if you need a large tree fast but not if you want a tree that will last longer than you. This champion willow is located right across from the main parking lot of Lake Nokomis by field #5 if you care to see it up close. The circumference of the trunk is 379 inches and it stands 70ft. tall with an average canopy spread of 73.5ft! What a monster!
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Jonathon Standing IN the monster!

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Even with decay regularly pruned out this tree is still huge!

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Thumbnail image for London Plane 3.JPGThis week's tree of the week is the London Plane Tree (Platanus x acerifolia). The London Plane Tree is a stately shade tree growing to a height of 70 feet tall. The mature bark is a stunning pale grey with exfoliating brown bark. The leaves resemble the look of a maple having a palmately lobed leaf. However, unlike a maple leaf, the London Plane Tree has a fussy back, giving it a unique character.

Being a zone 5 tree, The London Plane Tree is not commonly seen in Minnesota as it is not hardy to the northern climate. However, there are a few London Plane Trees scattered throughout St. Paul and Minneapolis. The slightly warmer temperature of the cities is often just enough for the London Plane Tree to survive the harsh Minnesota winter.

London Plane 2.JPGIn the team tree fields, we have three varieties of London Plane Tree, Exclamation!™, Columbia, and Bloodgood. All three varieties grew extremely well this season! It was exciting to see the trees grow from small 4-6 foot whips to a sizable 1" caliper trees (left image). This fall, we dug out most the London Plane Trees to prepare to plant in root trapper containers next spring!

The image bellow shows two of the four rows of London Plane Tree at the nursery. The lush, 12 foot strips of grass like plants growing in between the rows of trees are cover crop that team tree uses in all fields to keep the soil as healthy as our trees. The cover crop is a mixture of millet and buckwheat, both fast growing plants. The cover crop is used to maintain moisture in soil, reduce weed population, prevent wind erosion, and finally, increase soil organic matter. Often times, nurseries keep the soil bare by continuously spraying for weeds throughout the season to reduce the competition for resources. However, the benefit cover crop provides for the soil far out weights the marginal decreased caliper growth.
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The vigorous growth of the London Plane Tree is quite typical for the tree. The London Plane Tree is often used as street trees in warmer climates due to the vigorous growth and ability to withstand high compaction and atmospheric pollution. The number of tough tree species for urban situations is becoming less with the loss of American elm to Dutch elm disease and the more recent loss of Ash species to emerald ash borer. Both American elm and ash trees were extremely common street trees due to similar tough qualities the London Plane Tree has. With fewer and fewer street trees to withstand the tough street conditions, it is important to test the winter hardiness of different tough trees like team tree is doing with the London Plane Tree.

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We have been running a research project for the past 7 years on the Olson Memorial Highway median in North Minneapolis. This is a true proving ground for urban trees. There are multiple lanes of traffic on either side, lots of salt spray from cars, large mowers on small spaces, and 

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compacted soil to name a few challenges. This is not a friendly environment for trees, but it is just the place to do an evaluation on which trees work best in difficult urban environments.

There are 147 trees going down the boulevard, almost a mile and a half of them in a line. There have been a few necessary replacements, and most trees show signs of wear, but beyond all the salt damage and mower slashes, there are quite a few trees showing promise of high, wide crowns and stable trunks. On the right, Chad is holding a long (7 ft.!!) basal sprout coming from a Cathedral elm, (Ulmus davidiana var. japonica). Basal sprouts can cause trouble for urban foresters and arborists.  Nonetheless it is a good demonstration of the vigorous growth of elms and why they continue to be a popular tree in our urban forests.


The data collection took a whole day, starting and ending with a nice bike along the cedar lake trail (team tree gives it two thumbs up). Thankfully the weather cooperated and wasn't blazingly hot, or extremely windy. It was the most pleasant trip we have had to that site, and that is saying a lot for 6 hours between traffic.

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This week's tree is the Chinese catalpa (Catalpa ovata). They are easily recognized by their long thin pods and their heart shaped leaves. They differ from the native variety by having longer pods, and 

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purple tinted leaves. Just recently we planted a few flats of them in one of our fields, replacing the winter kill from last year.

Chinese catalpa is obviously not native plants, but they work well in Minnesota, and have been successful in urban environments.  A good example is still flourishing next to the stone arch bridge - 10 years after transplanting from our research nursery here at the U of MN. They grow in the USDA Hardiness Zones of 5-9, going to -20 or -30 F. The Chinese catalpa is a little squatter than the southern catalpa, growing to 20-30 feet. It was a special tree in china because its wood was used to make the bottom of the qin, a traditional Chinese instrument.


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 A full grown Chinese catalpa, down near the Stone Arch Bridge in SE Minneapolis


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Team Tree under the same, a tree that left our nursery 10 years ago


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Alongside foresters of the City of Saint Paul in a partnership with Excel Energy, we worked a full day this week putting the final touches on the trees at the new dog park near downtown Saint Paul. The park was converted from a train car and coal storage site into a spacious, beautiful inner-city gathering space complete with an astounding view of downtown Saint Paul.

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Tucked underneath the towering High Bridge, this 7-acre park features a large variety of trees, ranging from shade trees like the DED-resistant American elm Valley Forge, which will one day tower over the site, to the ornamental Showy Mountain Ash known for its beautiful white flowers. All told, 156 new trees were planted by excited volunteers on Arbor Day 2012.

Map of Trees on Site (click here)

Not only will these trees provide beauty and shade to the park, but serve as part of an ongoing study by the City of Saint Paul Forestry Unit and the Department of Horticultural Science at the University of Minnesota.  Aimed at testing the capability of various promising species to survive and flourish throughout the city and in harsh urban conditions in general like the compacted, coal contaminated soil of this particular site.

The grand-opening will be held Thursday, May 31st at 5:30 p.m. and will be hosted by Mayor Chris Coleman among others. Bring your pup, share in the excitement of Saint Paul's second City maintained dog park, and admire the growth of these young, beautiful trees!

Grand Opening Information



View High Bridge Dog Park in a larger map


--Charlie Lehnen--
(Student Lab Assistant; 2012)


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Project Update:

The opening on May 31st was a huge success. The park was filled with dogs and dog-owners alike, excited to check out the brand new park.  Among others, Mayor Chris Coleman and CEO of Excel Energy Judy Poferi brought their dogs to celebrate its opening.

The park hours are set from sunrise to sunset and normal dog park rules apply.

Exciting to watch both young trees and community continue to grow on this site.

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High Bridge Dog Park - Official Website


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On Arbor Day 2012 volunteers planted 156 trees near the High Bridge in Downtown Saint Paul!

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This new dog park will be home to several new varieties of trees! These new species are being 
tested for possible use throughout the city and will be tested for survival, performance, and growth rate. 

Different soil amendments will also be used to find new ways to establish trees on tough sites. This work is part of an ongoing research partnership between the City of Saint Paul - Forestry Unit and the Department of Horticultural Science at the University of Minnesota.
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