| Ulmus glaucescens | |
|---|---|
Scientific classification  | |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Angiosperms |
| Clade: | Eudicots |
| Clade: | Rosids |
| Order: | Rosales |
| Family: | Ulmaceae |
| Genus: | Ulmus |
| Subgenus: | U. subg. Ulmus |
| Section: | U. sect. Ulmus |
| Species: | U. glaucescens |
| Binomial name | |
| Ulmus glaucescens | |
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 2000–2600 m.[1]
Description
Although typically no more than 10 m in height, U. glaucescens can occasionally reach 18 m. Slow growing, the tree is possessed of a stiff branching pattern resembling that of a young American elm. The bark is longitudinally fissured and occasionally exhibits a peeling, mottled pattern. However, the tree is most easily distinguished by its small leaves; ranging from ovate to lanceolate, their size rarely exceeds 5 cm in length by 2.5 cm breadth, and are borne on twigs devoid of corky wings or layers. The perfect wind-pollinated apetalous 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. [2]
Cultivation
The tree is notable for its resistance to extreme drought which, combined with its high resistance to the elm leaf beetle in the United States, 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 20th century.[3] 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 in commerce.
Subspecies & varieties
Two varieties are recognized: var. glaucescens Rehder, and var. lasiocarpa L.K.Fu.
Accessions
- North America
- Brenton Arboretum, US. No accession details available.
- Morton Arboretum, US. Acc. nos. 429-2008, 537-76, 486-2016, 708-2016, 729-2016.
- United States National Arboretum Washington, D.C., US. Acc. nos. 76225, 76226, 76243, 76248.
- Europe
- Grange Farm Arboretum, Lincolnshire, UK. Acc. no. 1130.
References
- ^ 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. [1]
- ^ Miller, Fredric; Ware, George (2001-02-01). "Resistance of Temperate Chinese Elms (Ulmus spp.) to Feeding by the Adult Elm Leaf Beetle (Coleoptera: Chrysomelidae)". Journal of Economic Entomology. Oxford University Press (OUP). 94 (1): 162–166. doi:10.1603/0022-0493-94.1.162. ISSN 0022-0493. PMID 11233108.
- ^ Ware, G. (1995). Little-known elms from China: landscape tree possibilities. Journal of Arboriculture, (Nov. 1995). International Society of Arboriculture, Champaign, Illinois, US. [2] Archived 2007-11-30 at the Wayback Machine