American Elm

(Ulmus americana)

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http://commons.wikimedia.org/wiki/File:Img_ulmus_americana_2209.jpg

 

Leaves                         Bark                 Fruits     

        

http://commons.wikimedia.org/wiki/File:Ulmus_americana_JPG1F.jpg

http://commons.wikimedia.org/wiki/File:ElmBark.jpg

Fruits photo: Steve Hurst @ USDA-NRCS PLANTS Database

 

Family: Ulmaceae

 

Habitat: Moist deciduous woods, savannas,

woodland openings and borders. It also occurs

in wooded terraces and upland areas.

 

Range: Central and Eastern parts of North

America from Montana to Maine.  Saskatchewan,

Manitoba, Ontario and Quebec to Florida.

http://plants.findthedata.org/sites/default/files/958/media/images/American_Elm_Ulmus_americana_Plant.png

 

Physical Characteristics

 

Size and Form: Trees can be 60-100 feet

 tall with trunks of 2-4 feet in diameter.

Trees have a distinctive arching canopy.

 

Leaves: Green, alternate, 7-20 cm long with

double-serrated margins. The base of the

leaf is oblique.

 

Flowers: Flowers have both male and female

organs (= perfect) and can self-pollinate.  They

are small and purple-brown in color and emerge

before leaves in spring.

 

Fruits: A flat, 2 cm long samara (a winged

simple dry fruit that does not split open

along a seam) with a circular wing.

 

Interesting Facts

 

American elms were formerly the

predominant landscape tree in the

northeastern U.S.

 

The Washington Elm in Massachusetts

is where George Washington took command

over the American Continental Army.

 

The Liberty Tree in Massachusetts was a

rallying point for American resistance

towards England.

 

The species is tetraploid (having a double

compliment of chromosomes).

 

Dutch Elm Disease: This fungal disease was

introduced in the 1930's. It is responsible for

millions of American Elm deaths.  The disease

kills branches followed by the entire tree. 

The fungus grows in the water conducting parts

of the tree (xylem).  This causes water movement

to stop and wilting of leaves. The fungus enters the

tree through small wounds caused by beetles

feeding on tree branches.  Once inside the tree,

the fungus can move through the root system

of the diseased tree into the roots of nearby

healthy trees.

 

Restoration Efforts: There are efforts underway

to restore the American Elm.  Research to

develop elms tolerant of the fungus  has utilized

American Elms that are naturally growing and

reproducing (~ 1/100,000 elms tolerate the

disease). There have been plantings of Dutch

Elm Disease resistant elms in Ohio and the

Upper Mississippi Watershed.      

 

Webpage References:

http://www.clemson.edu/public/naturalist/2011_upstate_master_naturalist_class/pdf/three_tragedies.pdf

http://en.wikipedia.org/wiki/Ulmus_americana

http://na.fs.fed.us/fhp/ded/

http://na.fs.fed.us/spfo/pubs/pest_al/ded/elm.pdf

http://www.illinoiswildflowers.info/trees/plants/am_elm.html

Additional References:

Carley, Bruce. (2012) Saving the American Elm.  http://www.elmpost.org/

Schmidt, J. Frank & Warren, Keith.  (2005) The Return of the Elm The Status of Elms in the Nursery Industry in 2000.

 http://www.ces.ncsu.edu/fletcher/programs/nursery/metria/metria11/warren/elm.htm

Townsend, A. M., Bentz, S. E., and Douglass L. W. (2005).

Evaluation of 19 American elm clones for tolerance to Dutch Elm Disease.

Journal of Environmental Horticulture, March 2005, Horticultural Research Institute, Washington, D.C.