Shade Trees

The trees listed below are recommended for boulevards without overhead power lines. These varieties should do well in what are often tough planting sites. The boulevard widths (the area from curb to sidewalk) can range from 6-15 feet wide, depending on the subdivision. An 8-foot width is the norm. Given this planting area, the goal is to have a selection of hardy tree species that are medium to large in height (35-65 feet) to produce shade, slow down stormwater runoff, tolerate urban pollution, are relatively disease and insect free, and are aesthetically pleasing. *Note, descriptions cited from certain nurseries are not an endorsement of that nursery, these are just citations to give credit for the information.*

• Lindens
• Maple
• Elm
• Hackberry
• Honeylocust
• Amur Corktree
• Buckeye
• Kentucky Coffeetree
• Mountain Ash
• Ironwood
• Black Walnut
• Bur Oak
• Prairie Horizon Alder
• Gingko Biloba
• Northern Catalpa
• Birch

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Lindens

 

• A native tree species.
• Tend to perform well without major disease or insect problems.
• Drop fruit bracts in summer, can be messy.
• Flowers are loved by bees.
• Has a tendency to form poor branch unions without early structural pruning.
  

   

Description Sources: Gilman and Watson (1994), NDSU Agriculture and University Extension, NDSU North Dakota Tree Selector, University of Florida IFAS Extension, and Greenwood Nursery.

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Maple

• A popular tree that can struggle in alkaline soils.
• Clay County has alkaline soils, and this makes it more difficult for plants to take up iron and manganese, which can lead to iron chlorosis in maples. (yellowing leaves)
• Tend to be over planted, which can lead to problems during insect or disease outbreaks

Description Sources: MN Department of Agriculture, Morton Arboretum, and Missouri Botanical Society.

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Elm

 

• American Elm has been decimated by Dutch Elm Disease (DED) for decades.
• All varieties are DED resistant.
• Fast-growing and adaptable to tough sites.
• Elms need frequent pruning in the first 15 years to help trees develop with good structure and strong branch attachments.

 Descriptoin Sources: UMN Extension, Morton Arboretum, and Missouri Botanical Society. Photo: Chicagoland Grows.

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Hackberry

 

• Has been used to replace elms lost to DED.
• Has very unique bark and edible berries that can persist through the winter.
• "The name hackberry originated from the Scottish "hagberry" which in England was the common name for bird cherry. (Iowa State University)
• Tolerant to salt spray, pollution, and adaptable to many site locations.
• More prone to decay after wounding or with large prune cuts. These should be structured pruned young to minimize wounding.

Description Source: Iowa State University.

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Honey Locust

• Unique leaf structure gives dappled shade.
• Very adaptable to drought and multiple soil conditions.
• Medium sized tree that can be planted along boulevards or parking lots.
• Tolerant of road salt.

Description Sources: NDSU Woody Plant Improvement Program and Mortorn Arboretum.

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Amur Corktree

• Seems to be winter hardy and slow growing.
• No serious insect or disease problems.
• Only male trees will be planted.
• Prefers alkaline soils, moderately tolerant of road salt.

Description Sources: Morton Arboretum and UMN Agricultural Experiment Station.

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Buckeye

• Hardy tree for the area.
• Ohio Buckeye is prone to leaf scorch.
• Produces a nut that attracts wildlife.
• Produces many flowers in spring and nuts in fall that attract wildlife.
• Moderately tolerant of alkaline soils, soil salt, and salt spray.

Description Source: NDSU Woody Plant Improvement Program, NDSU Ohio Buckeye Handbook, UMN Agriculture Experiment Station, and Morton Arboretum.

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Kentucky Coffeetree

• Drought resistant, tolerant of pollution, and adaptable to a variety of soils.
• Slow to moderate growth rate.
• Forms a uniform, picturesque crown at maturity.
• Reaches height of 60-75'.
• Native to the Midwest.
• Large mammals that lived millions of years ago probably ate the pods and dispersed the seeds.
• "Native Americans made coffee from roasted, ground seeds (raw seeds are toxic), and European settlers apparently learned from them." (Missouri Department of Conservation)

Description Sources: Morten Arboretum and Missouri Department of Conservation.

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Mountain Ash

• Mountain ashes are members of the rose family, so they are not true ashes and are not hosts to the emerald ash borer.
• Tend to be small to medium-sized trees.
• Susceptible to problems with iron chlorosis and fire blight.
• Fruit attracts birds.
• Sensitive to road salt.

Description Source: Missouri Botanical Garden and Millcreek Nursery.

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Ironwood

• Smaller, native species.
• Has hop-like fruits, hence the alternative name, hop hornbeam.
• Resistant to many disease and insect problems.
• 20-40' in height, slow growing.
• Tolerates dry, alkaline, and clay soil.
• Intolerant of salt.
• Slow to establish.

Description: Morton Arboretum.

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Black Walnut

• A large oval to rounded, somewhat open-crowned tree.
• Used extensively by over 20 species of wildlife for food and cover.
• Produces walnuts.
• Needs to be sited carefully because it produces a chemical that is toxic to some plants.
• Grows to be 50-70' tall.
• Tolerates alkaline soil, clay soil, and road salt.
• One of the best woods for furniture among native trees.
• Native Americans reportedly used the husks of the nut to throw into ponds to poison fish and make them easier to catch. (Missouri Botanical Garden)

Description Source: Missouri Botanical Society.

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Oak

• Native.
• Produces acorns.
• Excellent tree for wildlife food and cover.
• Slow to moderate growth rate.
• Majestic crown and interesting bark.

Description Source: Missouri Botanical Society, Morten Arboretum, Bylands, and McKay Nursery.

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Prairie Horizon Alder

• Somewhat drought tolerant and can handle standing water.
  
• Medium to fast growth.
• Shade tolerant and also does well in sunny areas.
• Adaptable to many soil types.

Description Sources: NDSU Woody Plant Improvement Program and iTrees.com.

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Gingko Biloba

• This Species is being trialed for cold tolerance.

• Reaches a height of 50-80 feet.

• Tolerant of alkaline and acidic, compacted soils.

• Tolerant of air pollution, heat, and salt.

• Considered a living fossil, one of the longest-living tree species and has had fossils found from 270 million years ago.

Description Source: Arbor Day Foundation and Missouri Botanical Garden.

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Northern Catalpa

• Midwest native.
• Grows 40-60 feet tall.
• Seed pods persist through the winter.
• Tolerates alkaline and acidic soils, moderately tolerant to salt.
• Weak branch structure.
• Flowers attract pollinators.

Description Source: The Morton Arboretum.

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Birch

• Fast Growing.
• Can be a multi-stemmed tree or trained to be a single-stemmed tree.
• If birches are stressed, they can be susceptible to bronze birch borer and killed. (Bronze birch borer is a native borer and does not cause problems to otherwise healthy birch trees.)

Description Sources: Missouri Botanical Garden and NDSU Woody Plant Improvement Program.

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