American Elm State Tree of Massachusetts

The state tree of Massachusetts is the American Elm (Ulmus americana). This tree is also known as white elm, gray elm, swamp elm, water elm, soft elm, and Florida elm. The elm is indigenous throughout the United States. The tree is deciduous and is hardy to Zone 3.

The elm is harvested commercially for the manufacture of boxes, crates, caskets, and some tools. The wood warps and splits, which reduces its utility. It is also used as a fuel source.

The elm has lateral spreading roots that make is a good selection for preventing erosion. When the elm is planted in dry soil conditions, it can develop a taproot. It was widely planted as a street tree until being killed off by the Dutch elm disease which was spread by bark beetles starting in the 1930s. New strains have been developed since then that are sometimes successful in thwarting the disease.

American elm is known as a long lived and fast growing tree. It can grow to heights of 200 feet and attain 200-300 years of age. The trunk diameter can be as large as 4-5 feet. The trees prefer rich, well-drained loamy soil. Elms prefer full sun but will grow in part shade conditions. They are somewhat drought resistant.

The vase shape of the canopy makes the elm a popular choice for street trees and as specimen plantings in larger residential and park areas. When planted in rows, they are a reasonable wind screen. Their usefulness is enhanced because they are easy to transplant, resistant to city salt, and grow in a variety of soil pH levels. Healthy trees produce a great deal of seeds which can be a litter nuisance.

Elm seeds are enjoyed by small birds. Birds such as the grouse, bobwhite and partridge, as well as small animals like mice, squirrels, and the opossum, are known to eat the fruit which ripens in May and June from flowers that appear before the trees leaf out. Elm leaves are a dark green that turn yellow in the fall. The elm is not a showy fall tree.

American elm is propagated by cuttings and by seed. There are disease resistant cultivars available through the trade including 'Delaware #2', 'Jefferson', 'Liberty', 'New Harmony', 'Princeton', and 'Valley Forge'. The weak wood means the tree should be pruned to create a stronger structure.

American elm has predators besides the bark beetle. Elm is susceptible to wetwood, cankers, leaf curl, leaf spot, powdery mildew, aphids, elm leaf minor, elm borer, gypsy moth, mites, scales, and elm leaf beetle.

Sources
Ulmus americana, http://www.fs.fed.us/database/feis/plants/tree/ulmame/all.html
Ulmus americana, University of Connecticut, http://www.ipm.uconn.edu/Plants/u/ulmame/ulmame1.html
Ulmus americana, University of Florida, http://hort.ufl.edu/trees/ULMAMEA.pdf