Trees of Wisconsin
Ulmus americana L.
americana is a tree with alternate, simple leaves. The two sides of
the leaf base are often asymmetrical. The leaf margins are doubly toothed
(each large tooth often has a smaller tooth upon it). Leaves can be variable
in shape and size. Each fruit of an elm consists of a single seed,
surrounded by a flat, papery wing-like border. In the case of Ulmus
americana, the margin of the fruit is ciliate (straight, short hairs
along the margin), but the surface is glabrous. Ulmus thomasii
is our only other Elm with ciliate margins, and its surface is pubescent
(hairy). The progressively upward spreading
shape of the tree is characteristic.
Ulmus americana is found throughout Wisconsin. It does best in wet soils, especially in deciduous forests along the flood plains of streams, but is sometimes found in other forests and it can also do well in old fields and vacant urban soils. Many streets in Wisconsin were lined by large Elms before the spread of Dutch Elm disease killed most of the large elm trees (mostly in the 1970's and 80's in Wisconsin).