9. Ulmus pumila Linnaeus, Sp. Pl. 1: 326. 1753.
榆树 yu shu
Ulmus campestris Linnaeus var. pumila (Linnaeus) Maximowicz; U. pumila var. microphylla Persoon; U. manshurica Nakai.
Trees, to 25 m tall, d.b.h. to 1 m, deciduous. Bark dark gray, irregularly longitudinally fissured. Branchlets yellowish gray, glabrous or pubescent, unwinged and without a corky layer, with scattered lenticels. Winter buds dark brown to red-brown, ± globose to ovoid; inner bud scale margin usually white ciliate. Petiole 4-10 mm, pubescent; leaf blade elliptic-ovate to elliptic-lanceolate, 2-8 × 1.2-3.5 cm, abaxially pubescent when young but glabrescent or with tufts of hairs in vein axils or sometimes a few hairs on midvein and in forks of secondary veins, adaxially glabrous, base obliquely to symmetrically obtuse to rounded, margin simply or sometimes doubly serrate, apex acute to acuminate; secondary veins 9-16 on each side of midvein. Inflorescences fascicled cymes on second year branchlets, appearing before leaves. Perianth 4-lobed, margin ciliate. Samaras whitish tan, ± orbicular to rarely broadly obovate or elliptical, 1-2 × 1-1.5 cm, glabrous except for pubescence on stigmatic surface; stalk 1-2 mm; perianth persistent. Seed at center of samara or occasionally slightly toward apex but not reaching the apical notch. Fl. and fr. Mar-May. 2n = 28.
Slopes, valleys, plains; 1000-2500 m. Gansu, Hebei, Heilongjiang, Henan, Jilin, Liaoning, Nei Mongol, Ningxia, E Qinghai, Shaanxi, Shandong, Shanxi, Sichuan, Xinjiang, Xizang [Korea, Mongolia, E Russia; C Asia].
This species is cultivated throughout China.