| Ulmus glabra 'Nana' | |
|---|---|
 'Nana',Royal Botanic Gardens Edinburgh (1989) | |
| Species | Ulmus glabra |
| Cultivar | 'Nana' |
| Origin | Europe |
The dwarfwych elmcultivarUlmus glabra 'Nana', a very slow growing shrub that with time forms a small tree, is of unknown origin. It was listed in the Simon-Louis (Metz,France) 1869 catalogue asUlmus montana nana.[1][2]Henry (1913), referring his readers to an account of theKew specimen in the journalWoods and Forests, 1884,[3] suggested that it may have originated from awitch's broom. It is usually classified as a form ofUlmus glabra and is known widely as the 'Dwarf Wych Elm'. However, the ancestry of 'Nana' has been disputed in more recent years,Melville considering the specimen once grown atKew to have been a cultivar ofUlmus × hollandica.[4]
Not to be confused withLoudon'sU. campestris nana (1838), a dwarffield elm "with small, narrow, rough leaves",[5] or withUlmus 'Monstrosa', a long-petioled dwarf field-elm cultivar sometimes referred to as 'Nana Monstrosa'.[6][7]
The tree rarely exceeds 5 m in height, but is often broader.[8] The dark green leaves are smaller than the wych type, 5–9 centimeters (2.0–3.5 in) long, often with one or two cusp-like lobes either side of the apex.[7] The thick twigs, short petiole and diminutive samara with seed close to base, all point toU. glabra origin. A specimen atKew was described byHenry as 'a slow-growing hemispherical bush that has not increased appreciably in size for many years'.[2] Green describes 'Nana' as growing some 60 centimeters (24 in) in 10 to 12 years.[9]
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The low height of the tree should ensure that it avoidscolonization byScolytus bark beetles and thus remain free ofDutch elm disease. It has been noted that shrub-elms are usually less prone to infection.[10]
TheSpäth nursery of Berlin marketedU. montana nana in the late 19th century.[11] It was introduced to theDominion Arboretum,Ottawa,Canada, in 1898.[12]Ulmus montana nana, 'Dwarf Scotch Elm', was introduced to the USA in the late 19th century, appearing as a "new variety" in the 1897 catalogue of the Mount Hope Nursery (also known asEllwanger andBarry) ofRochester, New York.[13] A 'Nana' appeared asU. nana, 'Dwarf American elm', a "very small" elm with compact habit, in Kelsey's 1904 catalogue, New York.[14] (Other European elms described as 'American' by various nurseries include'Vegeta',[15]'Scampstoniensis',[16][17] and'Lutescens'.[2]) There was a well-grown specimen inMissouri Botanical Garden in the mid 20th century.[18] The tree is still occasionally found in arboreta and gardens in theUK, Europe and North America. It is not known inAustralasia. 'Nana' remains in cultivation in Europe (see Nurseries).
A shrub elm sold in the Netherlands asU. 'Monstrosa' appeared from its leaf and short petiole to be 'Nana',[19] while one cultivated in theRoyal Botanic Garden Edinburgh in the early 20th century as 'Nana' appears from its leaf and long petiole to have been 'Monstrosa'.[20] The current RBGE 'Nana' is the authentic wych clone (2017).
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The specimen of 'Nana' in theUniversity Parks (North Walk),Oxford, UK, has attained a height of about 6 m (2017).[21] Another grew inAlexandra Park,East Sussex, UK, measured 6 m high, 38 cm dia. at 1 m from ground in 1980 but is possibly now lost.[22]
None known