I've been perusing the Google Book American Forest Trees, by Henry H. Gibson. The book was published in 1913 and it isa gold mine of information on many native species. It is written principally from a timber perspective, but it is information rich on species geographical ranges, common names, structural features of different woods, historic uses, physical dimensions, etc. Ah yes, physical dimensions. Although Gibson must draw from other sources, he nonetheless often conveys what is typical versus exceptional for a species. For many species, he does pretty darn well. Here is an example. The quote below covers the eastern cottonwood.
Its range covers practically all of the United States east of the Rocky Mountains. It is rare or missing in eastern New England and southern Florida, and most abundant in the Mississippi valley, and there the largest trees are found. Some exceed 100 feet in height, and four in diameter. Extreme sizes of 140 feet in height with diameters of from seven to nine have been reported.
How do Gibson's dimensions jive with what we know today? Well, the cottonwood commonly exceeds 100 feet in height, but above 130 feet, the population of tall trees falls dramatically. Gibson's figure of a maximum of 140 feet is pretty close, and maximum girths of 7 to 9 feet is also close. In addition, the geographical area over which the cottonwood can reach or slightly surpass 130 feet is much greater than Gibson realized. As for girth, New York state is loaded with cottonwoods that exceed 4 feet in diameter, and there are plenty here in Massachusetts. That is for starters.
Nonetheless, Gibson wrote his guide in 1913. So, I'd give Gibson a pretty good mark for his cottonwood report. I wonder why so many tree guide authors who followed him failed to match his understanding. I wonder if the ridiculously high height maximum of 190 feet often listed for cottonwood came about from mis-measurements through the champion tree programs. Hmmm, could I be on to something? Still, other authors seem to have drawn from Gibson or Gibson's sources. Here are some examples of what noted sources/authors say.
Source: Identifying Trees
Author: Michale D. Williams
Cottonwood Dimensions: "reach matute sizes of over 100 feet in height and 4 feet in diameter at breast height"
Comments: Williams may have used Gibson. It is easy to find cottonwoods over 4 feet in diameter.
Source: The Sibley Guide to Trees
Author: David Allen Sibley
Cottonwood Dimensions: "Large tree often 60-90 feet tall (max. 170)"
Comments: e'd have to sit on the top of a cottonwood to hold it to 60 feet. We've never measured one to 170, and I don't expect we will.
Source: The Complete Trees of North America
Author: Thomas S. Elias
Cottonwood Dimensions: "Often reaching 120 feet in 30 years", "tall tree, 72 - 100 ft, rarely to 165"
Comments: Dr. Elias is a renown expert, but even he publishes conflicting and erroneous heights. The above description speaks for itself.
Source: Silvics of North America Vol II Hardwoods
Author: D.A. Cooper
Cottonwood Dimensions: "Eastern cottonwood is one of the tallest species east of the Rocky Mountains. Heights of 53 to 58 in (175 to 190 ft)"
Comments: This is one of the sources for the sometimes quoted 190-foot maximum.
More to come on other species.
Robert T. Leverett
Co-founder and Executive Director
Native Native Tree Society
Co-founder and President
Friends of Mohawk Trail State Forest