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This is a non-native and often invasive species.

Ulmus pumila
Ulmus pumila (Siberian Elm)
Ulmaceae (Elm Family)

Foothills. Roadsides, fields, lawns. Spring.
Near Yellowjacket Canyon, June 8, 2004.

Siberian Elms are a common roadside and farm tree and can be seen throughout the Four Corners region. Long lines of Siberian Elms have been planted as wind-breaks, and lone trees that have fifty-foot crown-spreads are common around farm houses. Birds find homes, bugs, and seeds in the Elms.  

Ulmus pumila was introduced from Asia and has spread widely because it is drought tolerant and produces numerous seeds which sprout and root easily, especially in areas that receive some moisture: roadsides, gardens, edges of buildings. Because Ulmus pumila does not choke waterways, does not reproduce in tangled thickets, and does not suck aquifers dry, it does not pose the same serious ecological problem as another common, non-native Southwest plant, Tamarisk. However, the relation of U. pumila to other plants in its adopted environment needs to be studied to determine how it might be changing to adapt to new environments and how it might be changing the ecological relationships in that new environment. Click to read a summary of Heidi Hirsch's research in these areas. And click again for an update from Heidi on her research. 

"Ulmus" is the classical Latin name, and "pumila" is Latin for "dwarf", although the tree does grow to fifty feet and is among the taller trees of the Southwest.

Ulmus pumila
Ulmus pumila (Siberian Elm)
Ulmaceae (Elm Family)

Foothills. Roadsides, fields, lawns. Spring.
Near Yellowjacket Canyon, June 8, 2004.

Although trees planted close to each other do not commonly exceed two feet in diameter, trees growing without competition can exceed four feet in diameter.

Ulmus pumila
Ulmus pumila (Siberian Elm) Ulmaceae (Elm Family) 

Foothills. Roadsides, fields, lawns. Spring. Near Yellowjacket Canyon, June 7, 2010.

Soft green leaves grow after flowers and seeds.

Ulmus pumila
Ulmus pumila (Siberian Elm)
Ulmaceae (Elm Family)

Foothills. Roadsides, fields, lawns. Spring.
Near Yellowjacket Canyon, February 24, 2004.

Winter shows the stretching, arching skeletal structure of these 50 foot Siberian Elms. Notice the downward leaning branches. The Elm on the right is about two feet in diameter. The fuzzy white area in this Elm just above the fence is snow-fall from the Red Winged Blackbirds that landed in the trees as I took the picture. 

Ulmus pumila (Siberian Elm)
Ulmaceae (Elm Family)

Foothills. Roadsides, fields, lawns. Spring.
Near Yellowjacket Canyon, March 11, 2004.

Warmer days came two weeks after the above snowy photograph was taken and buds swelled with new growth.

Ulmus pumila
Ulmus pumila (Siberian Elm)
Ulmaceae (Elm Family)
 

Foothills. Roadsides, fields, lawns. Spring.
Near Yellowjacket Canyon, April 21, 2010.

Ulmus pumila flowers are minute and packed into tight clusters (fascicles).

Each of the two clusters at left is about seven millimeters wide and three millimeters high on last year's stem growth of about two millimeters in diameter.

Numerous clusters are scattered over the latest few feet of growth of most branches of Ulmus pumila.

Ulmus pumila

Ulmus pumila

Ulmus pumila

Ulmus pumila (Siberian Elm)
Ulmaceae (Elm Family)
 

Foothills. Roadsides, fields, lawns. Spring.
Near Yellowjacket Canyon, April 20, 2010.

Ulmus flowers have no petals. The sepals are fused into a yellow/red cup calyx which has short lobes. The great macro-photograph below by Russ Kleinman from the Zimmerman Herbarium shows these details as well as the split and fringed style and the protruding filaments and anther sacs.

                                         Ulmus Pumila photo by Russ Kleinman, Western New Mexico University Department of Natural Sciences and the Dale A. Zimmerman Herbarium

Anthers turn to purple after pollination. 

The red lobes of the calyx wither more quickly than the rest of the calyx.

Six-to-fifteen flowers are bundled in a cluster.

Ulmus pumila       Ulmus pumila
Ulmus pumila (Siberian Elm)
Ulmaceae (Elm Family)
 

Foothills. Roadsides, fields, lawns. Spring.
Near Yellowjacket Canyon, April 20, 2010.

As flowers fade they take on various contorted shapes.

                     

Ulmus pumila seed production is monumental and since seeds readily germinate in any relatively moist areas (gardens, flower beds, edges of house foundations, roadsides), this non-native is a dominant tree in both towns and country-side in the Four Corners region.

In the two photographs immediately below, mature and immature Ulmus pumila trees appear to be covered in early spring green leaves, but the green actually belongs to tens of thousands of ripening fruits; leaves have not yet begun to grow.

Ulmus pumila

Ulmus pumila

Ulmus pumila

Ulmus pumila myriad of seeds on ground
Ulmus pumila (Siberian Elm)
Ulmaceae (Elm Family)
 

Foothills. Roadsides, fields, lawns. Spring.
Above: River Trail, Durango, April 27, 2016.
Left: Near Yellowjacket Canyon, June 7, 2010.

As the leaves begin to show about six weeks after flowers are fertilized,

Ulmus pumila seeds

 

 

 

       the seeds ripen         

                              

 

 

 

 

and then float to the ground in massive numbers.  If seeds fall in dry areas (such as the ground in the photograph at left) they have little chance of germinating, but if they fall in moist areas, they can sprout and grow quickly.

Range map © John Kartesz,
Floristic Synthesis of North America

State Color Key

Species present in state and native
Species present in state and exotic
Species not present in state

County Color Key

Species present and not rare
Species present and rare
Species extirpated (historic)
Species extinct
Species noxious
Species exotic and present
Native species, but adventive in state
Eradicated
Questionable presence

Ulmus pumila

Range map for Ulmus pumila