Ulmus
Ulmus is a genus of deciduous trees commonly called elms, recognized by asymmetrical leaves and winged fruits called samaras.
Samaras: Dry, winged fruits in which a seed is enclosed by a flattened membrane. Elm seeds mature inside the genus’s characteristic winged fruits.
Dutch elm disease: A fungal disease of elms spread chiefly by bark beetles and infected wood. The disease has killed millions of Ulmus trees and reshaped elm planting.
European white elm: Ulmus laevis, a European elm often found in floodplain forests. Its relative tolerance of Dutch elm disease contrasts with the severe losses of other elms.
Ulmus americana: The scientific name for the American elm, a species native to eastern North America. This species exemplifies the genus’s North American diversity and cultural history.
Leaf morphology: The study of leaf form, including shape, margins, venation, and arrangement. Elm identification often relies on leaf shape and asymmetrical bases.
American elm: Ulmus americana, a large North American elm once widely planted as a street tree. Its arching canopy made it a defining urban tree before Dutch elm disease.
Wych elm: Ulmus glabra, a broad-leaved European elm of forests and uplands. Its large leaves and ecological range distinguish it from commonly planted elms.
Ulmus minor: A variable elm native to Europe, western Asia, and North Africa. Its broad native range illustrates the genus’s diversity across the Old World.
Plant taxonomy: The science of naming, describing, and classifying plants. Ulmus species are grouped and named within a botanical classification system.
Siberian elm: Ulmus pumila, an elm native to eastern Asia and widely planted beyond its range. Its drought tolerance has made it useful in landscapes, but also invasive in some regions.