Friday, 25th. Journeyed over hills and dales — encamped on a stream affording plenty of grass, bitter cottonwood timber. It resembles the sweet cottonwood of Missouri, except the leaves are like those of the willow — distance 18 miles.
Cottonwood was useful as fuel, but it was also very important as forage for horses when snow was on the ground. You could keep your horses alive over the winter on cottonwood bark. However, horses would only eat the bark of sweet cottonwood, which they thrived on. Bitter cottonwood was shunned by horses.
For more information on bitter vs. sweet, read this blog entry from a Laramie-based botanist. That’s the source of these photos. Top to bottom: sweet cottonwood, bitter cottonwood, hybrid lance-leaf cottonwood.