American elm (Ulmus americana)
Large, height usually 50' to 70' with a diameter of 24" to 48", although it can reach a height of 100' with a diameter of up to 48"; wide-spreading branches that droop at the ends; crown is vase shaped.
Dark, ashy gray; divided into irregular, flat-topped, thick ridges; generally firm, although on older trees it tends to come off in flakes; outer bark layers alternating white and reddish brown in cross section.
Simple, alternate on stem, length 4" to 6"; rather thick, somewhat one sided, dark green, doubly toothed on margin, generally rough above, smooth below; veins very pronounced, running in parallel lines from mid rib to edge of leaf; turns yellow in autumn.
Winged samara, light green, oval, and waferlike in appearance; seed portion in center surrounded entirely by the wing; outer end of each wing deeply notched; seeds hang in clusters, ripen in spring, and are widely scattered by the wind.
Hardy throughout the state; more abundant on rich bottom lands in the southern half of Minnesota; moderately shade tolerant, fast growing. Very susceptible to Dutch elm disease.