Leaf: 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.
For more information see
http://www.dnr.state.mn.us/trees_shrubs/deciduous/americanelm.html.