The hybrid elm cultivar Ulmus × intermedia 'Willis' originated as a crossing made by a Mr Minnick of Kansas. Almost certainly derived from a crossing of the Siberian Elm Ulmus pumila (female parent) and the Red Elm Ulmus rubra, it was originally believed that the male parent was the American Elm Ulmus americana.[1]
| Ulmus × intermedia cultivar | |
|---|---|
| Hybrid parentage | U. pumila × U. rubra |
| Cultivar | 'Willis' |
| Origin | US |
Description
edit'Willis' was described as having a smooth grey bark, large leaves similar to U. americana, and capable of very rapid growth.[1]
Pests and diseases
editIn 1995 Santamour reported the cultivar "not widely tested for resistance to Dutch elm disease".[2] Elowsky, Jordon-Thaden, and Kaul (2013) refer to more recent papers on the subject.[3]
Cultivation
editFirst marketed by the Willis Nursery Co., Ottawa, Kansas, circa 1959,[2] it is not known whether the cultivar remains in cultivation in the United States, nor whether it was ever introduced to Europe or Australasia.
References
edit- ^ a b Green, Peter Shaw (1964). "Registration of cultivar names in Ulmus". Arnoldia. 24 (6–8). Arnold Arboretum, Harvard University: 41–80. Retrieved 16 February 2017.
- ^ a b 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.
- ^ Elowsky, C.G.; Jordon-Thaden, I.E.; Kaul, R.B. (10 July 2013). "A morphological analysis of a hybrid swarm of native Ulmus rubra Muhl. and introduced U. pumila L. (Ulmaceae) in southeastern Nebraska" (PDF). Phytoneuron. 2013–44: 1–23. ISSN 2153-733X. Archived from the original (PDF) on 5 October 2022. Retrieved 25 October 2017.