Ulmus pumila is a deciduous Tree growing to 15 m (49ft) by 12 m (39ft) at a fast rate.
It is hardy to zone (UK) 3 and is not frost tender. It is in flower in April, and the seeds ripen in May. The species is hermaphrodite (has both male and female organs) and is pollinated by Wind.
Suitable for: light (sandy), medium (loamy) and heavy (clay) soils and prefers well-drained soil. Suitable pH: acid, neutral and basic (alkaline) soils. It can grow in semi-shade (light woodland) or no shade. It prefers dry or moist soil and can tolerate drought. The plant can tolerates strong winds but not maritime exposure.
Ulmus pumila, the Siberian elm, is a tree native to Central Asia, eastern Siberia, the Russian Far East, Mongolia, Tibet, northern China, India (northern Kashmir) and Korea. It is also known as the Asiatic elm and dwarf elm, but sometimes miscalled the 'Chinese Elm' (Ulmus parvifolia). It is the last tree species encountered in the semi-desert regions of central Asia. Described by Pallas in the 18th century from specimens from Transbaikal, Ulmus pumila has been widely cultivated throughout Asia, North America, Argentina, and southern Europe, becoming naturalized in many places, notably across much of the United States.
The Siberian elm is usually a small to medium-sized, often bushy, deciduous tree growing to 25 m tall, the d.b.h. to 1 m; the bark is dark gray, irregularly longitudinally fissured. The branchlets are yellowish gray, glabrous or pubescent, unwinged and without a corky layer, with scattered lenticels. The winter buds dark brown to red-brown, globose to ovoid. The petiole is 4–10 mm, pubescent, the leaf blade elliptic-ovate to elliptic-lanceolate, 2-8 × 1.2-3.5 cm, the colour changing from dark green to yellow in autumn. The perfect, apetalous wind-pollinated flowers bloom for one week in early spring, before the leaves emerge, in tight fascicles (bundles) on last year's branchlets. However, flowers emerging in early February are often damaged by frost, consequently the species was dropped from the Dutch elm breeding programme.[9] Each flower is about 3 mm across and has a green calyx with 4–5 lobes, 4–8 stamens with brownish-red anthers,[10] and a green pistil with a two-lobed style.Unlike most elms, the Siberian elm is able to self-pollinate successfully.
The wind-dispersed samarae are whitish tan, orbicular to rarely broadly obovate or elliptical, 1-2 × 1-1.5 cm, glabrous except for pubescence on stigmatic surface; the stalk 1–2 mm, the perianth persistent. The seed is at centre of the samara or occasionally slightly toward apex but not reaching the apical notch. Flowering and fruiting occur March to May. Ploidy: 2n = 28. The tree also suckers readily from its roots.
The tree is short-lived in temperate climates, rarely reaching more than 60 years of age, but in its native environment may live to between 100 and 150 years. A giant specimen, 45 km southeast of Khanbogt in the south Gobi, with a girth of 5.55 m in 2009, may exceed 250 years (based on average annual ring widths of other U. pumila in the area).
