A U. S. National Arboretum introduction, frontier elm is a hybrid between the smooth-leaved elm Ulmus minor and Chinese elm Ulmus parvifolia. Our specimens by the Krasberg Rose Garden, planted in 1995, are turning into beautiful trees with nice, straight trunks and branches that arch outward. The leaves are small and toothed. Fall color is an outstanding rich red, with central veins that often remain green. It was one of many attempts to replace the American elm with hybrids resistant to Dutch elm disease. This pyramidal tree grows to a height of 40 feet with full sun to partial shade and moderate moisture conditions. From July through October, it produces inconspicuous yellow-green blooms, but it not known to produce seeds.