I have visited both of the largest known cottonwood trees in Kansas. The largest Eastern Cottonwood is near Studley in eastern Sheridan County in northwest Kansas. According to the Kansas Forest Service, this tree is over 35 ft in circumference (measured 4.5 ft off the ground), is 96 ft tall, and has a spread of 127 ft at the crown.
The largest Plains Cottonwood tree in Kansas is off West 4th Avenue on Avery Rd in western Reno County. I actually think this tree is more massive on it's trunk since is is tighter packed. I have visited this tree several times. It is almost 31 ft in circumference, 90 ft tall, and has a spread of 98 ft. Notice the size of the trunk in the photo below compared to me with outstretched arms. Note: the Poison Ivy did not seem to bother me.
Plains Cottonwood trunk with me in front
Female cottonwood trees produce the fluffy white seeds in the spring to early summer that gives the tree it's name. See the photo below which shows a cottonwood seed shower I was in near Arlington, KS.
Cottonwood Seed Shower
I also enjoy traveling down lanes with cottonwood trees lining both sides. A good example of this is a stretch of Herren Rd south of Greenfield Rd in Reno County, KS.
Herren Road Cottonwoods
Also, another custom that attracts people to cottonwood trees is to attach something to the tree. There is a cottonwood tree near Wetmore in northeast Kansas, that people have been nailing shoes to for over 20 years. See the article about this tree at the following address on the Kansas Sampler Foundation's web pages:
This tree inspired another. On a large cottonwood tree on his farm near Partridge, Jay Yoder has started a tree with license plates (tags). Nails and a hammer are provided so you can put your license plate on the tree facing towards your home. Karen and I visited this tree this past weekend and put her Indiana license on the tree facing northeast - See the photo below.
Jay Yoder's license plate Cottonwood
In conclusion, it's no wonder that the cottonwood tree has been named the official Kansas state tree.