The hybrid elm cultivar Ulmus × intermedia 'Improved Coolshade' is a superior selection from cultivated seedlings of 'Coolshade' (U. rubra × U. pumila), by Arthur O. Wild of Sarcoxie Nurseries, Sarcoxie, Missouri, United States. It was patented and released by him in 1958. Wild did not use the cultivar name 'Improved Coolshade' (later adopted by Santamour and Bentz[1]) in his patent claim, the assuption being that the superior clone would replace the same nursery's original 'Coolshade'.[2]
| Ulmus × intermedia 'Improved Coolshade' | |
|---|---|
| Hybrid parentage | U. rubra × U. pumila |
| Cultivar | 'Improved Coolshade' |
| Origin | Sarcoxie, Missouri, US |
Description
editThe tree is similar to 'Coolshade', but faster growing, with a straighter trunk and more symmetrical branching. The foliage is described as "abundant and relatively dense", with leaves averaging 3 inches in length by 1.75.[2]
Pests and diseases
editAlthough reputedly resistant to Dutch elm disease, it had not been (by 1995) widely tested.[1] Wild reported it "moderately resistant to Dutch elm disease, as determined by inoculation tests and reports by the U. S. Department of Agriculture".[2]
Cultivation
edit'Improved Coolshade' was noted for its drought tolerance. It is not known whether the tree remains in cultivation in North America, nor whether it was introduced to Europe or Australasia.
Synonymy
edit- 'Primus' (earlier name for the cultivar).
Accessions
editReferences
edit- 1 2 Santamour, Frank S.; Bentz, Susan E. (May 1995). "Updated Checklist of Elm (Ulmus) Cultivars for use in North America". Journal of Arboriculture. 21 (3): 122–131. Retrieved 20 June 2016.
- 1 2 3 United States Plant Patent, 9 September 1958, Plant Patent Info.: PP1,747; includes three photographs
- ↑ 'Coolshade' at Central Experimental Farm Arboretum, Ottawa, Ontario
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