Siberian Elm vs Chinese Elm

These two introduced species are often confused, but mature trees are easy to tell apart by their bark, and the species are also easily told apart by leaves, seeds, or timing of flowering.

Siberian Elm (Ulmus pumila)	Chinese Elm (Ulmus parvifolia)
Siberian Elm (Ulmus pumila) An elm that is occasionally planted in landscaping and has widely escaped cultivation in both the cooler and drier parts of North America.	Chinese Elm (Ulmus parvifolia) A small-leafed elm with mottled bark that occasionally escapes from landscaping in North America.
Siberian Elm (Ulmus pumila) Mature trees have rugged, gray bark with long vertical furrows. Photo © Nate Martineau, CC BY 4.0.	Chinese Elm (Ulmus parvifolia) Mature trees have smooth, thin, mottled bark with an orangeish color on inner layers. Photo © https://www.inaturalist.org/photos/16939726, CC BY 4.0.
Siberian Elm (Ulmus pumila) Leaves are usually more symmetrical at the base. Photo © Nate Martineau, CC BY 4.0.	Chinese Elm (Ulmus parvifolia) Leaves are often more strongly asymmetrical at the base. Photo © C., Public Domain.
Siberian Elm (Ulmus pumila) Seed takes up a smaller portion of the samara. Photo © Christian Grenier, Public Domain.	Chinese Elm (Ulmus parvifolia) Seed takes up a larger portion of the samara. Photo © Alison Northup, CC BY 4.0.

References & External Resources

These short lists show only links helpful for ID. For a complete list of references and resources also covering other aspects of ecology, visit the links section of the full article on each plant, which is the first entry here.