Large-fruited Elm
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| Ulmus macrocarpa Hance |
The Large-fruited Elm Ulmus macrocarpa is a small deciduous tree or large shrub endemic to the Far East excluding Japan. It is notable for its tolerance of drought and extreme cold and is the predominant vegetation on the dunes of the Korqin sandy lands in the Jilin province of north-eastern China, making a small tree at the base of the dunes, and a shrub at the top [1]. As is obvious from its name, the tree is distinguished by its large, orbicular, wafer-like samarae < 50 mm in diameter. The tree can reach a height of 17 m, with a slender trunk rarely exceeding 0.4 m d.b.h. (diameter at breast height). The bark is longitudinally fissured, and dark grey in colour. The twigs often develop corky wings that may persist for several years. The leaves are usually obovate, up to 9 cm in length, and chiefly characterized by their thick, leathery texture. The wind-pollinated petal-less flowers appear from March until May, and the seeds from April to June.
Possessed of a moderate resistance to Dutch elm disease, and a low susceptibility to elm yellows, the tree has been assessed at the Morton Arboretum, Illinois, for its landscape potential, and is now considered suitable for open areas such as parks and campuses. It has also proven very resistant to the Elm Leaf Beetle Xanthogaleruca luteola in trials in Oklahoma [2]. However, it is intolerant of poorly-drained ground prone to waterlogging. By the age of ten years, the tree bears a close resemblance to the American Elm U. americana, but will never approach the latter's size.
The species was introduced to the Arnold Arboretum, Massachusetts, in 1908 and is also cultivated at the Holden Arboretum, Ohio. Young, potted plants are commercially available from several specialist elm emporia in the USA. In the UK it was introduced to the erstwhile Aldenham Park, Hertfordshire, by Vicary Gibbs in the 19th century, but is now grown at the Royal Botanic Garden Edinburgh, the Sir Harold Hillier Gardens in Hampshire, and the NCCPG elm collection [3] held by Brighton & Hove City Council. It is now considered rare and endangered in its native China.
[edit] References
- Bean, W. J. (1981). Trees and shrubs hardy in Great Britain, 7th edition. Murray, London.
- Fu, L. & Jin J. (eds). (1992). China Red Data Book. Rare and endangered plants. Vol. 1. Science Press, Beijing.
- 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. [4]
- Ware, G. (1995). Little-known elms from China: landscape tree possibilities. Journal of Arboriculture, (Nov. 1995). International Society of Arboriculture, Champaign, Illinois, USA.
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