Water-elm

Water-elm Planera aquatica is single species in the southeastern U.S.A., a small deciduous tree 10-15 m tall, closely related to the elms but with a prickly nut 10-15 mm diameter, instead of a winged seed. It grows, as the name suggests, on wet sites. The leaves are 3-7 cm long, with a serrated margin.

It is moderately susceptible to Dutch elm disease.