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

Tuesday, March 10, 2009

What kind of a maple is it?

Hybridization of maple species

Usually, a positive identification of a maple tree can be made with a tree field guide and a close look at the bark and leaves of the tree.

However, if you're really perplexed about the identification, you might be looking at a hybrid maple, a cross between two different maple species. This can happen in areas where two maples species bloom simultaneously. It occurs commonly enough that an entire chapter of the book, Maples of the World, is devoted to hybrid maples.

Black and sugar maple hybrids

In the eastern United States, hybrids of black maple (Acer nigrum) and sugar maple (Acer saccharum) are common, according to the U.S. Forest Service Sylvics Manual and other sources.

The black and sugar maples have crossed and backcrossed so many times that the two species are nearly indistinguishable in some areas. In other areas, the black maple still retains its own unique characteristics.

There appear to be two broad populations of black maple with respect to its hybridizing with sugar maple. One is in the western part of its range, where it maintains its identity and shows little tendency to cross with sugar maple. The second population is in the eastern section, where it hybridizes readily with sugar maple. (Source: U.S. Forestry Sylvics Manual)

Red and silver maple hybrids

George Ware of the Morton Arboretum writes "Natural hybridization between red and silver maples is fairly common in the swamp and streamside forests of eastern Wisconsin and eastwood to New England " (source: pdf). Hybridization is also reported in southern Canada. In these regions, red and silver maples bloom at the same time, and the trees grow in similar habitats.

Because the blooming periods of silver and red maple overlap, there is a possibility of natural hybridization between them. Under controlled artificial conditions, the two species hybridize easily, producing prolific seed sets. The hybrids are intermediate between their parents in leaf characters. Their growth was much faster than that of red maple seedlings but did not equal that of silver maple. Source: U.S. Forest Service Sylvics Manual

In fact, red/silver hybrids have a name -- Acer x freemanii or Freeman maple -- and a number of named cultivars, including  Jeffersred (patented as "Autumn Blaze"), Armstrong, Celzam (patented as "Celebration:), and others. The name Acer x freemanii is pronounced "Acer hybrid freemanii".

Related: A comparison of the leaves of red, silver, and Freeman maples

3 comments -- please add yours:

new york city garden said...

My question then is: Are hybrids of red maple and silver maple stronger than the silver maple parent. Or is the hybrid's wood still soft and breakable like the silver maple. I like silver maples appearance, but tougher wood would be an advantage.

Genevieve said...

As I was researching this post, I read over and over that Freeman maples don't have as big a problem with narrow crotches between their branches as silver maples do. The crotches tend to have a wider angle on the Freeman. However some of the sources also noted that the Freeman maple's wood is brittle like the silver maple.

So, I think it's safe to say that they won't break up as bad as silver maples -- but given a major storm, expect damage.

Personally, I wouldn't plant one close to my house, after the experience we've had with silver maples.

new york city garden said...

Thanks, Won't do that!

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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."

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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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