The

hybrid Hybrid may refer to: Science * Hybrid (biology), an offspring resulting from cross-breeding ** Hybrid grape, grape varieties produced by cross-breeding two ''Vitis'' species ** Hybridity, the property of a hybrid plant which is a union of two dif ...

elm

cultivar A cultivar is a type of cultivated plant that people have selected for desired traits and when propagated retain those traits. Methods used to propagate cultivars include: division, root and stem cuttings, offsets, grafting, tissue culture ...

''Ulmus × intermedia'' 'Willis' originated as a crossing made by a Mr Minnick of

Kansas Kansas () is a state in the Midwestern United States. Its capital is Topeka, and its largest city is Wichita. Kansas is a landlocked state bordered by Nebraska to the north; Missouri to the east; Oklahoma to the south; and Colorado to th ...

. Almost certainly derived from a crossing of the Siberian Elm ''

Ulmus pumila ''Ulmus pumila'', the Siberian elm, is a tree native to Asia. It is also known as the Asiatic elm and dwarf elm, but sometimes miscalled the 'Chinese Elm' ('' Ulmus parvifolia''). ''U. pumila'' has been widely cultivated throughout Asia, No ...

'' (female parent) and the Red Elm ''

Ulmus rubra ''Ulmus rubra'', the slippery elm, is a species of elm native to eastern North America. Other common names include red elm, gray elm, soft elm, moose elm, and Indian elm. Description ''Ulmus rubra'' is a medium-sized deciduous tree with a spre ...

'', it was originally believed that the male parent was the American Elm ''

Ulmus americana ''Ulmus americana'', generally known as the American elm or, less commonly, as the white elm or water elm, is a species of elm native to eastern North America, naturally occurring from Nova Scotia west to Alberta and Montana, and south to Flor ...

''.

Description

'Willis' was described as having a smooth grey bark, large leaves similar to ''U. americana'', and capable of very rapid growth.

Pests and diseases

In 1995 Santamour reported the cultivar "not widely tested for resistance to

Dutch elm disease Dutch elm disease (DED) is caused by a member of the sac fungi (Ascomycota) affecting elm trees, and is spread by elm bark beetles. Although believed to be originally native to Asia, the disease was accidentally introduced into Americas, America ...

". Elowsky, Jordon-Thaden, and Kaul (2013) refer to more recent papers on the subject.

Cultivation

First marketed by the Willis Nursery Co., Ottawa,

, circa 1959, 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

{{DEFAULTSORT:Ulmus x intermedia 'Willis' Ulmus × intermedia cultivar Ulmus articles missing images Ulmus