Elm leaves are alternate, with a toothed edge and a base that is lopsided.
Identifying elm
Scientific name: Ulmus
How to recognise it
- Alternate, simple leaves, in two rows along the twig.
- Leaf base asymmetric, with one side reaching lower on the stalk than the other.
- Edge double-toothed, with prominent side veins running straight to the teeth.
- The fruit is a flat round samara with the seed in the middle.
Species
- American elm (Ulmus americana): vase-shaped; leaves smooth to slightly rough; ridged bark in layers.
- Slippery elm (U. rubra): very rough, sandpapery leaves, and a sticky, aromatic inner bark.
- English elm and wych elm in Britain; the wych elm has big, rough leaves and a short stalk.
Shape
The American elm was a classic vase-shaped street tree. Dutch elm disease killed a great many of them in the twentieth century, so mature elms are now much less common in many places.
Look-alikes
Hackberry has lopsided leaves too, but smooth edges near the base and warty bark. Basswood has heart-shaped, lopsided leaves with single teeth. Beech has straight side veins but a symmetrical base.
Elms today
Resistant cultivars of American elm have been bred and planted in towns. Mature elms that survive are worth protecting, and the risk of Dutch elm disease can be reduced by prompt removal of infected wood.