Burke: Ulmus pumila vs. Ulmus americana

	Ulmus pumila	Ulmus americana
	Siberian elm	American elm
Habit		Trees 21-35 m. tall, the crowns spreading, commonly vase-shaped; branches pendulous, the old-growth branches smooth; wood soft. Bark light brown to gray, deeply fissured; twigs brown, glabrous to pubescent.
Leaves		Leaves glabrous to pubescent, with a petiole about 5 mm. long; blades oval to oblong-ovate, 7-14 cm. long and 3-7 cm. wide, the base oblique, the margins doubly serrate, the tip pointed.
Flowers		Flowers on branches of previous season, appearing before leaves; flowers in bundles up to 2.5 cm. in diameter, drooping, on pedicles 1-2 cm. long; calyx with 7-9 shallow lobes; petals none; stamens 7-9, the anthers red; stigmas white, deeply divided.
Fruits		Samaras ovate, 1 cm. long, narrowly winged, creamy-yellow, sometimes tinged with reddish-purple.

	Ulmus pumila	Ulmus americana
Flowering time	February-April	February-April
Habitat	Roadsides, fence rows, waste areas.	Woodlands, pastures, old fields at low to moderate elevations.
Distribution	Occurring chiefly east of the Cascades crest in Washington; introduced over much of the North America, where commonly escaping and naturalizing. [WildflowerSearch map] [BONAP county map]	Occurring on both sides of the Cascades crest in Washington; native to eastern and central North America, though escaped from cultivation elsewhere. [WildflowerSearch map] [BONAP county map]
Origin	Introduced from Asia	Introduced
Conservation status	Not of concern	Not of concern
Sibling taxa	U. americana, U. parvifolia, U. procera	U. parvifolia, U. procera, U. pumila
Web links	Local floras: BC, CA, OR, WA Local Web sites: CalFlora, CalPhotos, Flora NW, PNW Herbaria WildflowerSearch iNaturalist (observations) USDA Plants Database LBJ Wildflower Center SEINet Plants of the World Online Encyclopedia of Life Wikipedia Google Image Search	Local floras: BC, CA, WA Local Web sites: CalFlora, CalPhotos, Flora NW, PNW Herbaria WildflowerSearch iNaturalist (observations) USDA Plants Database LBJ Wildflower Center SEINet Plants of the World Online Encyclopedia of Life Wikipedia Google Image Search

Trees 21-35 m. tall, the crowns spreading, commonly vase-shaped; branches pendulous, the old-growth branches smooth; wood soft. Bark light brown to gray, deeply fissured; twigs brown, glabrous to pubescent.

Leaves

Leaves glabrous to pubescent, with a petiole about 5 mm. long;

blades oval to oblong-ovate, 7-14 cm. long and 3-7 cm. wide, the base oblique, the margins doubly serrate, the tip pointed.

Flowers

Flowers on branches of previous season, appearing before leaves;

flowers in bundles up to 2.5 cm. in diameter, drooping, on pedicles 1-2 cm. long;

calyx with 7-9 shallow lobes;

petals none;

stamens 7-9, the anthers red;

stigmas white, deeply divided.

Fruits

Samaras ovate, 1 cm. long, narrowly winged, creamy-yellow, sometimes tinged with reddish-purple.