By Len Phillips, ASLA Emeritus
Some municipal arborists tend to use the same tried-and-true plant list every year when selecting trees for planting in their city. However, this practice tends to result in a monoculture that could be bad if an unknown pest comes along and wipes out one of those favorite species. Plus, it can become monotonous visually.
Because a lot of new trees come out every year that are being bred for urban tolerance, arborists should do some experimenting to check them out. It doesn’t hurt to have a plant list that contains 50 percent of your tried-and-true species and 50 percent new species or cultivars to try out. It may be worthwhile to conduct some trials on your own city streets even if you only plant six new trees. I can personally attest to the fact that I have found some great new trees for my city, and I have also had a few failures that I will not plant again. I have been very surprised at how some unknown trees have been remarkable new additions to our plant list, and have replaced some of the usual suspects. The failures are easily replanted next year.
The following is a list of some new introductions, as well as a few older cultivars that are not well known but should be grown in more cities. I have noted cases where some trees perform better in some regions but not in others.
Acer x freemanii ‘Autumn Blaze’ — Autumn Blaze Maple — 50 feet tall and 40 feet wide, Zone 3, upright branching with a broadly oval form and medium-green summer foliage with very long-lasting orange-red leaves in the fall. This hybrid combines the drought tolerance of the silver maple with the fall color of the red maple.
Acer ginnala ‘JFS-UGA’ — Red November Maple — 18 feet tall and 24 feet wide, Zone 5, low-branched with bright-green summer foliage and red leaves in the fall. This fine-textured tree, selected by Dr. Michael Dirr, tolerates the heat of Georgia and will do well throughout the southeast United States.
Acer rubrum ‘Autumn Flame’ — Autumn Flame Red Maple — 35 feet tall and 35 feet wide, Zone 3, rounded form with medium-green summer foliage and early bright-red leaves in the fall. This is one of the hardiest of the red maples, is seedless, and has small leaves.
Acer rubrum ‘Brandywine’ — Brandywine Red Maple — 40 feet tall and 30 feet wide, Zone 4, oval form with dark-green summer foliage that turns deep red in the fall. This tree was introduced by the U.S. National Arboretum and is seedless. The tree produces its fall color much later than other red maples. Besides producing the best red fall color, it is very well adapted to the southeast United States.
Acer rubrum ‘Frank Jr.’ P.A.F. — Redpointe Red Maple — 45 feet tall and 30 feet wide, Zone 4, broadly pyramidal form with dark-green summer foliage that turns bright red in the fall. This J. Frank Schmidt & Son nursery introduction has fast growth and excellent branching structure. The strong upright form makes this tree an excellent street tree and it has consistent fall color.
Acer rubrum ‘Sun Valley’ — Sun Valley Red Maple — 40 feet tall and 35 feet wide, Zone 4, oval form with dark-green summer foliage turning bright red in the fall. This U.S. National Arboretum introduction is seedless and is resistant to leafhopper damage. Branching is very dense. Although this tree was developed in 1982, it is just now becoming popular.
Acer saccharum ‘Reba’ — Belle Tower Sugar Maple — 45 feet tall and 18 feet wide, Zone 5, has a narrow oval form with bright-green summer foliage that turns orange-yellow in the fall. This tree grows very well in the heat and humidity of southeastern United States. It was introduced by Auburn University.
Acer saccharum ‘Morton’ — Crescendo Sugar Maple — 45 feet tall and 40 feet wide, Zone 4, broad oval with dark-green summer foliage turning orange and red in the fall. This tree tolerates the heat and humidity of the Midwest, and was selected by the Morton Arboretum.
Acer saccharum ‘Bailsta’ — Fall Fiesta Sugar Maple — 50 feet tall and 40 feet wide, Zone 4, broadly oval form has large, shiny, dark green leaves in summer foliage turning orange, red, and yellow in the fall. This tree is one of the best for heat tolerance and was selected by Bailey Nurseries.
Acer saccharum ‘John Pair’ — John Pair Sugar Maple — 30 feet tall and 30 feet wide, Zone 5, rounded shape with glossy green summer foliage and red leaves in the fall. This heat-resistant tree was selected by Dr. John Pair from a ‘Caddo’ Maple in Oklahoma.
Cornus kousa x nuttalli ‘KN 30-8’ — Venus Dogwood — 25 feet tall and 20 feet wide, Zone 5, upright oval shaped with deep-green leaves that become purple to red in fall. This tree is has very large blooms that are as much as six inches in diameter and are a creamy-white in color. The tree is nearly sterile and is another Elwin Orton and Rutgers University introduction.
Fraxinus pennsylvanica ‘Oconee’ — Georgia Gem Ash — 50 feet tall and 35 feet wide, Zone 6, upright oval with glossy deep-green summer foliage and yellowish leaves in the fall. This heat resistant tree was selected by Dr. Michael Dirr as a seedless green ash cultivar for the south. The leaves are bigger than almost any other ash. This tree should not be grown where Emerald Ash Borer is present or even nearby.
Ginkgo biloba ‘JFS_UGA2’ — Golden Colonnade Ginkgo — 45 feet tall and 25 feet wide, Zone 4, narrow oval shape that has medium green summer foliage that turns bright-yellow in the fall. This tree was discovered by Dr. Michael Dirr and is ideal for use on narrow streets. The tree is male and seedless.
Ginkgo biloba ‘The President’ — Presidential Gold Ginkgo — 50 feet tall and 40 feet wide, Zone 4, broad oval to pyramidal shape with medium-green summer foliage that turns bright yellow in the fall. This tree was selected by Dr. Michael Dirr and sets a new standard for ginkgos. It is male and seedless.
Gleditsia triacanthos ‘Harve’ — Northern Acclaim Honeylocust — 45 feet tall and 35 feet wide, Zone 3, is broadly pyramidal in shape with medium-green leaves that turn yellow in the fall. This tree is extremely cold hardy and was selected by Dale Herman at North Dakota State University.
Malus ‘Adirondack’ — Adirondack Crabapple — 18 feet tall and 10 feet wide, Zone 4, densely branched and upright form with medium-green leaves that become yellow in the fall. This tree is resistant to the four major diseases of Crabapple and provides a very heavy bloom of white flowers followed by bright-red fruit. This U.S. National Arboretum introduction was developed by Don Egolf.
Malus ‘Purple Prince’ — Purple Prince Crabapple — 20 feet tall and 20 feet wide, Zone 4, rounded shaped with purple leaves that become bronze-green in summer foliage and maroon fruit. This tree is resistant to the four major diseases of Crabapple and is probably the best purple-foliaged crabapple on the market today.
Malus ‘JFS-KW5’ — Royal Raindrops — 20 feet tall and 15 feet wide, Zone 4, upright spreading shape and cut leaf purple leaves in summer that turn bright pinkish-red in the fall. The red fruits are persistent all winter long. This tree is resistant to the four major diseases of Crabapple, has a plant patent number 14375, and is very popular with those who have tried it.
Phellodendron lavallei ‘Longenecker’ — Eye Stopper Cork Tree — 40 feet tall and 35 feet wide, Zone 4, upright and rounded with medium-green summer foliage that turns bright yellow in the fall. This selection from the University of Wisconsin Longenecker Gardens has the clearest bright-yellow foliage among the cork trees.
Platanus x acerifolia ‘Yarwood’ — Yarwood Planetree — 50 feet tall and 40 feet wide, Zone 6, broadly pyramidal shape with large light-green summer foliage that turns brownish-yellow in the fall. This tree was selected by the University of California and has high resistance to powdery mildew and anthracnose. This tree thrives in the southwest United States, and it will also do very well in the southeast. However in the northwest, Yarwood is not a good selection and the older Bloodgood or Liberty are better choices. In the east, the Bloodgood and Columbia cultivars are the best to grow for disease resistance.
Pyrus calleryana x betulaefolia<ITAL] ‘Edgewood’ ‘Edgewood’ — Edgewood Pear — 30 feet tall and 25 feet wide, Zone 5, rounded form with silvery-green summer foliage that turns reddish purple in the fall. This tree, with a plant patent number 10151, is loaded with white blooms in spring and is a fast growing callery pear that cannot be beat in the east.
Tilia cordata x mongolica<ITAL] ‘Harvest Gold’ — Harvest Gold Linden — 40 feet tall and 30 feet wide, Zone 3, pyramidal form with deep-green summer foliage that turns bright golden-yellow in the fall. This tree, plant patient number 12232, is fast growing and very hardy. It has been considered the best full-size linden for several years.
Ulmus japonica x wilsoniana ‘Morton’ — Accolade Elm — 70 feet tall and 60 feet wide, Zone 5, vase shaped with arching branches and dark-green summer foliage that turns yellow in the fall. This tree is resistant to the elm leaf beetle and tolerates DED and Phloem Necrosis. This hybrid was selected and tested by Morton Arboretum. It does well in the northwest and upper Midwest, but not too well in the southeast United States.
Ulmus ‘Morton Glossy’ — Triumph Elm — 55 feet tall and 45 feet wide, Zone 5, upright, oval to vase shaped, with glossy dark-green summer foliage that turns yellow in the fall. This tree tolerates DED and Phloem Necrosis. This hybrid is another selection from Morton Arboretum. It does very well in the northwest.
Zelkova serrata ‘Musashino’ — Musashino Columnar Zelkova — 45 feet tall and 15 feet wide, Zone 5, very narrow vase shape and medium-green summer foliage that turns yellow in the fall. This tree is ideal for use on narrow streets. The upright branches allow vehicle and pedestrian clearance underneath them.
Zelkova serrata ‘Schmidtlow’ — Wireless Zelkova — 24 feet tall and 36 feet wide, Zone 5, has a broadly spreading form with medium-green summer foliage that turns red in the fall. Its low height and broad spread, for which the tree was selected, make it an ideal street tree.
Len Phillips, ASLA Emeritus is administrator of Online Seminars for Municipal Arborists — http://on-line-seminars.com. He can be reached via e-mail at email@example.com.
Editor’s note: Red November, Redpointe, Belle Tower, Crescendo, Golden Colonnade, Presidential Gold and Triumph are all trademarked terms. Autumn Blaze, Autumn Flame, Fall Fiesta, Venus, Georgia Gem, Northern Acclaim, Royal Raindrops, Edgewood, Accolade and Wireless are all registered terms.
* Dirr, Michael, “New Shade Trees in the American Landscape”, Nursery Management & Production, January 2007 and February 2007.
* “Reference Guide”, J. Frank Schmidt & Son Co., 2007