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

Tuesday, February 23, 2010

Identifying cottonwood in winter

Populus deltoides (aka Eastern cottonwood, Eastern poplar)

Several characteristics of the mature Eastern cottonwood (Populus deltoides) make it easy to identify, even at a distance.

  • Height -- The Eastern cottonwood is typically very tall, up to 100 feet in height in favorable conditions. The crown can be as wide as the tree's height, if it is not crowded by other trees.
  • High crown -- The lowest branches may not be within reach; rather, they may be high overhead. Cottonwoods aren't trees that invite climbing.
  • Massive branches -- The limbs usually head off from the trunk in a somewhat upright direction, and they are large and long. If the limbs appear delicate in comparison to the trunk, it's probably not a cottonwood. As the branches grow longer, they tend to arch a little, giving the tree a vase-like shape.
  • Rugged and often ragged shape -- The tree has weak wood, and its branches often break in heavy storms. Dead wood is a light gray or nearly white, after the bark falls off.
  • Moist location -- The Eastern cottonwood loves any site with damp ground. This includes stream and pond banks, road ditches, moist ravines, floodplains, swamp edges, and any other area with plenty of moisture. It even tolerates standing in water for short periods of time. (Cottonwood also tolerates dryer sites, but often it was introduced to such places, rather than growing there naturally.)
As the observer draws closer to the tree, another distinctive feature becomes evident:

  • The rough bark of the trunk and large branches has deep vertical furrows, and its color is ash gray. In contrast, the bark of the twigs is light tan or yellowish brown -- though the twigs may be too high in the air to see them clearly!
And last but not least, look for brown, triangular leaves with long stems and zigzag edges, lying on the ground below the tree. (The word deltoides in the cottonwood's Latin name means triangular, like a river delta.)

I am rather fond of cottonwood trees because so many grew on the grounds of the one-room country school I attended in northern Nebraska. I believe they were Eastern cottonwoods rather than the closely-related plains cottonwood.

Our schoolhouse sat on a low meadow. Water often stood on one end of the playground in winter (we ice-skated at recess), and in spring when the snow and ice melted, the road ditches became little streams. It was a perfect place for cottonwoods.

The cottonwoods grew on three of the four sides of the school grounds. They were great for hide-and-seek. A few of the trunks were so large that several children could hide behind them -- what fun!

My schoolmates and I were upset when our fathers got together one day and cut down one of our favorite trees for hiding. It was old, and they were afraid it was going to drop limbs on the schoolhouse.

I took three of the photographs in this post in Christian County, KY. The little clump of cottonwoods in the top photo grows in a low spot near the Hopkinsville High School. Water collects there whenever there's a heavy rain. I took the two creek-bank photos in eastern Christian County. The stream is the South Fork of Little River, near its origin.

Credit for the great photo looking straight up the cottonwood trunk: USDA-NRCS PLANTS Database / Herman, D.E., et al. 1996. North Dakota tree handbook. USDA NRCS ND State Soil Conservation Committee; NDSU Extension and Western Area Power Administration, Bismarck.

6 comments -- please add yours:

Kathleen Cain said...

Hey, thanks for the interesting cottonwood posting. Amazing to me how these trees adapt to different geography. Yours (eastern--and think you might have swamp cottonwoods out that way, too, P. heterophylla L.) not lending themselves to climbability--out here in the west, ours closer to the ground (plains, lanceleaf, and narrowleaf)though just as interesting and "erratic" (love that about them in the wild.

Kathleen Cain, author
The Cottonwood Tree: An American Champion (Johnson Books/Bigearth Publishing. Boulder: 2007).

P.S. I'm not a scientist, either; just an English major who should have taken more biology classes!


Good identification post! It helps that you explained where they grow and the bark photos are very helpful. Thanks -- barbara

JimK said...

Cottonwoods grew all over my neighborhood growing up in Rochester, NY. When they set their cotton in the spring it often drifted so deep that everyone would dig out their snow shovels to clear the driveway. If you didn't and it rained the cotton would stick and be there for months. I remember filling those big yard waste bags full of cotton. I haven't seen any since moving to Kentucky, but I'm slowly replanting a streamway/easement near my house with natives, so maybe I'll add a cottonwood to my list.

KaHolly said...

Hi! What a valuable site about trees! I am so glad I found your blog. I am going to put it in my favorite places to use as a reference! ~karen

ECD said...

I recognize that cottonwoods have a place in the natural ecosystem, but please think of those of us who have allergies when you are making a planting decision and choose another species!

Genevieve said...

Some people are allergic to cottonwood pollen. Some people think they are allergic to cottonwood pollen because they have symptoms at the time that cottonwood seeds are in the air. However, the cottonwood pollen is released about 6-8 weeks before the seeds are released. The real culprit is usually grass pollen which is released at about the same time the cottonwood seeds are released.

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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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