Ulmus pumila
Siberian elm

Steve Dewey, Utah State University, Bugwood.org

Description: Siberian elm is a fast-growing tree in the elm family (Ulmaceae) distinguished by small toothed leaves about 1-2? in (3-7 cm) long and half as wide, and pointed at the tip. Unlike other elms, the leaf base is usually symmetrical, forming a nearly even "V". Leaves are smooth and dark green above, paler and nearly hairless beneath, and alternate from side to side along twigs. Mature trees reach a height of 50-70 ft. (16-22 m.), with a round crown of slender, spreading branches. The bark is rough, gray or brown, and shallowly furrowed at maturity. Twigs are nearly hairless with small, blunt buds. Flowering occurs in the springtime. The small greenish flowers lack petals and occur in drooping clusters of 2 to 5. After flowering, a single seed forms in the center of each smooth, flattened, circular, ? in (10-15 mm) wide fruit.

Other species of elms (Ulmus) and the close relative Zelkova, especially younger plants, look similar to Siberian elm. Some may even confuse it with choke-cherry (Prunus serotina) and hackberry (Celtis sp.). The native slippery elm and American elm typically have leaves that are greater than 3 in (7.3 cm) long, with unequal heart-shaped leaf bases, and leaf margins with double teeth.