Grow in average, medium moisture, well-drained soils in full sun. Tolerant of light shade. Prefers rich, moist loams. Adapts to both wet and dry sites. Generally tolerant of urban conditions.
Ulmus americana, commonly called American elm, is a medium to large deciduous tree, typically growing to 60-80’ (less frequently to 130’) tall with a vase-shaped, broad-rounded crown. It is native to eastern and central North America. In Missouri, it typically occurs in low moist ground and along streams throughout the state (Steyermark). Although once widely planted as a street and lawn tree, American elm populations have been so decimated by Dutch elm disease that this tree is no longer considered to be a viable selection for landscape uses. Insignificant small green flowers appear in spring before the foliage emerges. Flowers give way to single-seeded wafer-like samaras (each tiny seed is surrounded by a flattened oval-rounded papery wing). Seeds mature in April-May as the leaves reach full size. Rough-textured, ovate-elliptic, dark green leaves (to 6” long) have toothed margins and asymetrical bases. Leaves typically turn an undistinguished yellow in fall.
Genus name comes from the Latin name.
Specific epithet means of North or South America.
Dutch elm disease, a fatal fungal disease spread by airborne bark beetles, attacks the water-conducting tissue of the tree, resulting in wilting, defoliation and death. Phloem necrosis is a disease caused by a phytoplasma that attacks the food-conducting tissue of the tree, usually resulting in a loosening of the bark, wilting, defoliation and death. Wetwood is a bacterial disease that results in wilting and dieback. Various wilts, rots, cankers and leaf spots may also occur. Insect visitors include borers, leaf miner, beetles, mealy bugs, caterpillars and scale.
Development of varieties that are resistant to Dutch elm disease is ongoing.
May be used as a lawn, shade or street tree. Not currently recommended for most landscape plantings due to Dutch elm disease. Disease resistant varieties such as Ulmus americana ‘Valley Forge’ are promising but not totally immune.