Ulmus glaucescens

Taxobox
status = LC
name = "Ulmus glaucescens"
regnum = Plantae
divisio = Magnoliophyta
classis = Magnoliopsida
ordo = Rosales
familia = Ulmaceae
genus = "Ulmus"
species = "U. glaucescens"
binomial = "Ulmus glaucescens"
binomial_authority = Franch.

"Ulmus glaucescens" Franch. the Gansu Elm, is a small deciduous tree from the northern provinces of China, where it is found along river valleys and on mountain slopes at elevations of between 2000 m and 2600 m Fu, L., Xin, Y. & Whittemore, A. (2002). Ulmaceae, in Wu, Z. & Raven, P. (eds) "Flora of China", Vol. 5 (Ulmaceae through Basellaceae). Science Press, Beijing, and Missouri Botanical Garden Press, St. Louis, USA. [http://flora.huh.harvard.edu/china/PDF/PDF05/Ulmus.pdf] ] .

Description

Although typically no more than 10 m in height, it can sometimes reach 18 m. The bark is longitudinally fissured and occasionally exhibits a peeling, mottled pattern. However, the tree is most easily distinguished by its small leaves. Although ranging in shape from ovate to lanceolate, their size rarely exceeds 5 cm x 2.5 cm, borne on twigs devoid of corky wings or layers. The wind-pollinated petal-less flowers are produced on second-year shoots in March - April; the samarae are elliptic, < 25 mm long, and can remain on the tree until the end of May.

Pests and diseases

The tree is resistant to Dutch elm disease; it is also very resistant to the Elm Leaf Beetle "Xanthogaleruca luteola".

Cultivation

The tree is notable for its resistance to extreme drought which, combined with its high resistance to the elm leaf beetle in the USA, has made it a contender for establishment on the Great Plains. Like most other Asiatic species, it is intolerant of wet ground. The tree is very rare in cultivation, but was one of a number of Chinese elms assessed for their horticultural potential at the Morton Arboretum, Illinois, during the last quarter of the 20 th century Ware, G. (1995). Little-known elms from China: landscape tree possibilities. "Journal of Arboriculture", (Nov. 1995). International Society of Arboriculture, Champaign, Illinois, USA. [http://www.ces.ncsu.edu/fletcher/programs/nursery/metria/metria8/m87.pdf] ] . It is not known to have been introduced to Europe or Australasia. There are no known cultivars of this taxon, nor is it known to be available from any nurseries.

ubspecies & varieties

Two varieties are recognized: var. "glaucescens" Rehder, and var. "lasiocarpa" L.K.Fu.

Accessions

;North America
*Morton Arboretum, Illinois. No accession details available.

References