Feature Tree Archives - August 2000


Common Name: American Elm

Scientific Name: Ulmus americana

Family: Ulmaceae

This Tree in Colorado: American elm is a tree that continues to grace the streets and avenues of our cities and towns. It's characteristic vase-shaped branching habit makes it one of the finest street trees around. Dutch elm disease reeked havoc on the large leafed elms for the last 60 years. Many streets lost their beauty and shade. However, good sanitation practices now make it worth attempting growing elms once again in our parks, along our streets and in our years.


  Habit: A graceful vase-shape in most situations. Other types of growth patterns include spreading and upright.

Landscape Value: Still valued. With the ability to control the spread of Dutch elm disease, more cities are replanting this majestic trees. They have tremendous value it providing good branching conditions for over streets and sidewalks. The drawback to elms are all the insects and diseases that seem to affect it. The list is long. But still, American elms are a stately tree and should be replanted. However they should not be replanted to a monoculture density as they were in the past.

Hardiness:  Zones 2-9. A wide range of temperature tolerance.

Leaves: 
Simple; alternate; oblong-obovate; 4" to 6" long, 1" to 3" wide; deciduous; coarsely doubly serrate margin; dark green; glabrous or slightly rough above.

Flowers: Samara about  1/2" long; oval; a flat thin wing around the see, wing hairy-fringed and notched at tip.

Fruit:  

Bark: Ash-gray; divided into flat-topped ridges with diamond-shaped furrows in between; a broken piece of outer bark will have alternating light and dark layers.

Insects and Diseases: Besides Dutch Elm disease, common diseases include wetwood, black leaf spot, and branch cankers. Common insect pests include cankerworms and aphids. Deer browse damage can be serious on young trees.

 

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