elm family (Ulmaceae)
American elm (Ulmus americana) -- in September -- Williams, Fort Collins Natural Area, Larimer County, CO
Siberian elm (Ulmus pumila) -- in February -- Spring Creek Trail, Fort Collins, CO green & brown
Siberian elm (Ulmus pumila) -- in April -- Bellvue, Larimer County Foothills, CO
Siberian elm (Ulmus pumila) -- in September -- Springer, Fort Collins Natural Area, Larimer County, CO