Plants of the Eloise Butler Wildflower Garden

Siberian Elm is an introduced and naturalized invasive medium size tree growing to 70 feet high with an open crown, but often badly formed due to limb breakage and sprouting along the trunk. The wood is very brittle.

The bark is gray to brown becoming irregularly furrowed with interlacing ridges and usually streaked with lighter stains from a bacterial infection.

Twigs are slender, slightly zigzag, grayish-green, leaf buds are small and round (about 1/8 inch) while the flower buds are also round but larger, both with very dark reddish-black scales which, on the flower buds, can have fine hair.

The leaves are alternate, narrowly elliptic to ovate, stalked, 2 to 3 inches long, no more than 1 inch wide, with a singly-toothed (saw-toothed) margin, dark green on top and smooth whereas the underside is paler, usually smooth but may have some hair in the vein axils. The lateral veins fork up to 3 times per side. The leaf tip is pointed and the base is more rounded than other elms and mostly symmetrical. Fall color is a dull yellow.

Flowers of Siberian Elm, like all of the Ulmus genus, are bisexual, appearing before the leaves. The flowers form in tight clusters (fascicles) along the twigs, opening erect with (3) 6 to 15 un-stalked flowers per cluster, each flower with 4 or 5 shallow calyx lobes and no petals; 4 to 8 stamens with reddish-brown anthers, a green pistil with a long divided style. Flowers are pollinated by the wind.

Seed: The fertile flowers form a wafer-like almost round single seeded samara, about 1/2 inch in diameter, most of the diameter is a broad thin wing. These are a creamy-yellow turning brown at maturity. The papery wing of the samara is NOT hairy on the edges; the the tip is notched from 1/3 to 1/2 of its length. The seed itself is thickened but not inflated. These mature rapidly in late spring to early summer and are dispersed by the wind. They can germinate immediately and the prolific seed production can produce many small trees in areas not controlled by mowing.

Habitat: Siberian Elm in its native habitat grows in moist soils along stream edges. It has a widely spreading root system. In North America it has been planted as a landscape plant and as a windbreak, being adaptable to various soils in sunny conditions. It is resistant to the Dutch Elm disease that has devastated the native American Elm. It is subject to wilts, rots and elm leaf beetles.

Names: The genus Ulmus, is the Latin word for Elm. the species name, pumila, means 'dwarf' and refers to the small leaf of this species compared to other members of the genus. This is where the alternate common name of 'dwarf elm' arises. The author name for the plant classification, 'L.' refers to Carl Linnaeus (1707-1778), Swedish botanist and the developer of the binomial nomenclature of modern taxonomy.

Comparisons: U. pumila is similar to Chinese Elm, U. parvifolia, but there the bark is smooth and sheds in irregular tan to orange plates; grows in shade and flowers and fruits in the fall. Other native elms in our area, such as American Elm and Slippery Elm, have leaves with more un-symmetrical bases and the leaf margins are double toothed. American Elm flowers are stalked.