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

Saturday, June 21, 2008

Northern and Southern Catalpas

One way to identify the native catalpas

The catalpa trees have bloomed recently in Christian County, Kentucky. I don't know if the catalpa in these photos is a southern catalpa (Catalpa bigenoides) or a northern catalpa (Catalpa speciosa). The northern catalpa is sometimes called a hardy catalpa. It is found in USDA Zones 4-8, whereas the southern catalpa prefers Zones 5-9.

I might have made a guess about the identity of this catalpa if I had looked closely at its blossoms. The northern catalpa's blossom is supposed to be more thickly spotted on the inside, but how would you know without a southern catalpa blossom to compare it with?

According to tree expert William H. Lamb, writing for the American Society of American Foresters in 1912, a reliable clue to identification can be found within the catalpa bean. The long, thin pod of the catalpa (up to 18 or 20 inches in length) contains a septum or partition along which the beans are arranged. If the septum is flat and thin, the tree is a southern catalpa. If the septum is round, the tree is a northern catalpa. The advantage of this identifier is that one doesn't need to compare specimens from both catalpas.

Being able to distinguish between the two catalpas was important to foresters in 1912. Though catalpa wood is soft, it was a favored wood for railroad ties and fence posts because it is durable in contact with soil.

Northern catalpa wood was harder than southern catalpa wood, and thus superior for railroad ties, particularly as trains grew heavier. Farmers wanted to grow and harvest northern catalpas, selling the largest part of the trunk for railroad ties and smaller parts for fence posts. Some railroads even had plantations of northern catalpa.

In addition, the hardy catalpa was considered a good candidate for the treeless American prairies. Though it prefers a moist situation, the hardy catalpa can endure dry conditions and cold winters. I can vouch for this myself. Two big catalpa trees grow in the sandy, often arid. front yard of my brother's ranch in Kansas.

I'm rather fond of catalpas, but that may be because I've never had one. In favorable locations, they can be so prolific that they're considered invasive. They're also a rather messy tree, when those big leaves and pods drop.

Furthermore, the catalpas aren't even listed in the bible of wildlife value -- Martin, Zim, and Nelson's American Wildlife and Plants. When this book was published in 1951, apparently no report had been made of an animal eating any part of a catalpa tree, anywhere in the U.S., ever.

4 comments -- please add yours:

Eastcoastdweller said...

The catalpa is the favored home/food of a certain caterpillar, though -- a caterpillar for which catfish have a great fondness. How they developed that fondness before anglers brought the two together is beyond me, though.

Genevieve Netz said...

It might have been from unfortunate caterpillars who lost their grip and fell into the water from catalpa leaves, do you think?

Mark said...

We have two huge catalpas in the backyard of our home of 20 years. I jut wanted to offer an opinion on your comment that catalpsa are messy. I guess it depends. The blossoms are spectacular and form a white snow-like ring around the tree as they fall. They wiil turn brown eventually, but shrivel up so much that the first time you mow over them they disintegrate.

Same with the bean pods. Any that drop late or hold on until spring will easily mulch under the mower.

The leaves are a different story. They are so large and numerous and heavy that they become difficult to rake. Better to mulch them with the mower a little at at ime as they fall. When dry, they too disintegrate fairly well.

The thing about the pods, though, is that they very much resemble a small, brown snake lying in the grass, Twenty years of getting used to them and I still get startled once in a while when I first see an isolated one that has dropped late.

Also, regarding the catepillars, our neighbor up the road from my mom and dad's farm had catalpa trees. I used to go over there with my dad, an avid fisherman, and collect them. Dad called them "Ka-tau-bee worms". "Ka-tau-bee" being the local pronunciation I guess in Southern-central Illinois. I never knew they were called "Ca-tal-pas" until later in life.

Finally, as I recall, the "worms" were a bit smaller than tomato worms and brightly colored - greenish-yellow with black vertical stripes, I think. I don't remember for sure, that was a long time ago. But I have never seen any such worms on my trees and not sure why they were on our neighbor's trees. Maybe they were destined to become moths or butterflies further South than I am now (Heyworth, Illinois). Dad also used them for catfish bait.

Jonàs said...

Apparently it is a good nectar source for bees.

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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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