| 词条 | Ulmus × intermedia 'Willis' |
| 释义 |
| name = Ulmus × intermedia cultivar | hybrid = U. pumila × U. rubra | cultivar = 'Willis' | origin = US }} 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] Description'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'Willis' has not been widely tested for resistance to Dutch elm disease.[2] CultivationFirst 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. References1. ^1 {{cite journal |last=Green |first=Peter Shaw |authorlink=Peter Shaw Green |date=1964 |title=Registration of cultivar names in Ulmus|url=https://archive.org/stream/arnoldiaarno_21#page/40/mode/2up/|journal=Arnoldia |volume=24|pages=41–80 |number=6–8 |publisher=Arnold Arboretum, Harvard University |access-date=16 February 2017}} {{Elm species, varieties, hybrids, hybrid cultivars and species cultivars |state=collapsed}}{{DEFAULTSORT:Ulmus x intermedia 'Willis'}}2. ^1 {{cite journal |last1=Santamour |first1=Frank S. |last2=Bentz |first2= Susan E. |date=May 1995 |title=Updated Checklist of Elm (Ulmus) Cultivars for use in North America|url=http://joa.isa-arbor.com/request.asp?JournalID=1&ArticleID=2673&Type=2|journal=Journal of Arboriculture |volume=21 |number=3|pages=122–131 |access-date=20 June 2016}} 3 : Ulmus × intermedia cultivar|Ulmus articles missing images|Ulmus |
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