Tree Notes is about trees -- especially native trees, trees for wildlife, and trees in history.

Thursday, May 21, 2009

Ten invasive non-native trees of the South

Alien trees that threaten southern ecosystems

The USDA Forest Service Southern Regional Task Force for the Assessment of Nonnative Invasive Species has compiled a list of invaders that they believe to be a very grave threat to forest and grassland ecosystems of the South. This "High Priority" list includes 121 non-native, invasive species -- and 10 of them are trees.

On the list:
  1. Tree of heaven, ailanthus -- Ailanthus altissima
  2. Silktree, mimosa -- Albizia julibrissin
  3. Russian olive -- Elaeagnus angustifolia
  4. Chinaberry tree -- Melia azedarach
  5. White mulberry -- Morus alba
  6. Paulownia, princess tree, royal empress -- Paulownia tomentosa
  7. Octopus tree, schefflera (in southern Florida) -- Schefflera actinophylla
  8. Brazilian peppertree (in Florida and southern Texas) -- Schinus terebinthifolius
  9. Saltcedar -- Tamarix ramosissima
  10. Tallowtree, Chinese tallowtree -- Triadica sebifera

Eight of these trees also appear on the Invasive Plants of the Eastern United States list at

According to the Executive Order on Invasive Species signed by President Clinton in 1999, an alien (non-native) species is invasive when its "introduction does or is likely to cause economic or environmental harm or harm to human health."

May 22 is The International Day for Biological Diversity, and the theme is "Invasive Alien Species". A booklet, Invasive Alien Species: A Threat to Biodiversity (pdf) can be downloaded. In observation of the day, I've written this post to help increase awareness of some invasive trees that are (or may become) a big problem in the southern United States.

2 comments -- please add yours:

Garry said...

Tried sending an email and it bounced. I moved here to Metcalfe County Kentucky 5 years ago--have never seen a cottonwood tree and am wondering why. Had many of them in Illinois where I grew up. If you can answer my question please email me

my blog

Genevieve said...

I don't know why you haven't seen any cottonwoods there. We certainly have them in Christian County along rivers and creeks and in low-lying areas.

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Enrich your life with the study of trees.

"The power to recognize trees at a glance without examining their leaves or flowers or fruit as they are seen, for example, from the car-window during a railroad journey, can only be acquired by studying them as they grow under all possible conditions over wide areas of territory. Such an attainment may not have much practical value, but once acquired it gives to the possessor a good deal of pleasure which is denied to less fortunate travelers."

Charles Sprague Sargent (1841-1927)

Print references I frequently consult

Benvie, Sam. Encyclopedia of North American Trees. Buffalo, NY: Firefly, 2000.

Brockman, C. Frank. Trees of North America: A Guide to Field Identification. Ed. Herbert S. Zim. New York: Golden, 1986.

Cliburn, Jerry, and Ginny Clomps. A Key to Missouri Trees in Winter: An Identification Guide. Conservation Commission of the State of Missouri, 1980.

Collingwood, G. H., Warren David Brush, and Devereux Butcher. Knowing Your Trees. Washington: American Forestry Association, 1978.

Dirr, Michael. Dirr's Hardy Trees and Shrubs: an Illustrated Encyclopedia. Portland, Or.: Timber, 1997.

Elias, Thomas S. The Complete Trees of North America; Field Guide and Natural History. New York: Book Division, Times Mirror Magazines, 1980.

Grimm, William Carey. The Book of Trees;. Harrisburg, PA: Stackpole, 1962.

Hightshoe, Gary L. Native Trees, Shrubs, and Vines for Urban and Rural America: a Planting Design Manual for Environmental Designers. New York: Van Nostrand Reinhold, 1988.

Little, Elbert L. National Audubon Society Field Guide to North American Trees. New York: Chanticleer, 1996.

Martin, Alexander C., Herbert S. Zim, and Arnold L. Nelson. American Wildlife and Plants. New York: McGraw Hill, 1951.

Mitchell, Alan F., and David More. The Trees of North America. New York, NY: Facts On File Publications, 1987.

Randall, Charles E. Enjoying Our Trees. Washington: American Forestry Association, 1969.

Settergren, Carl D., and R. E. McDermott. Trees of Missouri. Columbia: University Extension, 1995.

Sternberg, Guy, and James W. Wilson. Native Trees for North American Landscapes: from the Atlantic to the Rockies. Portland: Timber, 2004.

Wharton, Mary E., and Roger W. Barbour. Trees and Shrubs of Kentucky. Lexington: University of Kentucky, 1973.

Wyman, Donald. Trees for American Gardens. New York: Macmillan, 1965.

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