Ulmus 'Purpurea'

Ulmus

'Purpurea' foliage, Brighton, UK
Cultivar 'Purpurea'

The elm cultivar Ulmus 'Purpurea' K.Koch [1] is probably synonymous with the tree listed by Henry (1913) as Ulmus montana (: glabra) var. atropurpurea,[2] raised at the Späth nursery in Germany c.1881 but later classed as a cultivar by Boom in Ned. Dendr. 1: 157, 1959.[3] Henry also listed an Ulmus campestris (:U. minor 'Atinia') var. purpurea Petz. & Kirchn.,[4][5] with a description matching that of 'Purpurea', and adding that though it was grown at Kew as U. montana (:glabra) var. purpurea it was "probably of hybrid origin".

The ancestry of the tree remains obscure, but the fact that 'Purpurea' occasionally produces suckers suggests an Ulmus minor hybrid origin. F. J. Fontaine conjectured U. glabra × U. minor 'Stricta',[6] placing it in the Ulmus × hollandica group. Both the leaves and the habit of 'Purpurea' appear to support this conjecture. However, U. glabra occasionally produces red- or purple-flushed new leaves; an elm in the gardens of the Hedvig Eleonora Church, Östermalm, Stockholm, is listed as Ulmus procera 'Purpurea', but in form, fruit and foliage it appears to be a wych elm with a purplish tinge to its leaves.[7] In Europe there is also a putative small-leaved elm Ulmus minor 'Purpurascens'.

In Australia cultivars by the name of U. glabra 'Purpurea', U. procera 'Purpurea' and U. purpurea appear in old nursery catalogues dating from 1886, but these are now believed to be synonymous with the cultivar currently known there as U. × hollandica 'Purpurascens',[8] the name given by F. J. Fontaine to 'Purpurea'.[9][10] An elm obtained in 1922 from H. Kohankie & Son was listed by the Morton Arboretum, Illinois, as Ulmus procera 'Purpurea',[11] but without description.

In North America, purple-leaved elms encountered in the fall are likely to be the new hybrid Ulmus 'Frontier'.

Description

'Purpurea' grows to > 25 m in height, and is short-trunked with open, straggling, ascending branches. The bark has a reddish-brown hue. The leaf-buds are long, sharply pointed and dark purple, on shoots of the same colour. The flowers, too, emerge a uniform dark purple. The fruit, tinged purple, is small and intermediate between U. glabra and U. minor. The leaves, which are slightly folded, have a brief purplish-green flush in spring. The new leaves of lower bole-shoots and of suckers are pure dark purple, without any green.[12][13][14] After the spring flush, the leaves become olive green then darken in the summer - perhaps the darkest green of all the elms. Their underside is paler, so that, with their increasing fold as the year progresses, the late-summer foliage has a greyish hue.[8]

Pests and diseases

The tree is susceptible to Dutch elm disease. A specimen at the Ryston Hall arboretum in Norfolk, England, obtained from the Späth nursery in Berlin before 1914[15] was killed by the earlier strain of Dutch elm disease in the 1930s.

Cultivation

In Europe the cultivar U. × hollandica 'Purpurascens' was "produced in quantity" by nurseries in Oudenbosch, the Netherlands.[16] It appears to have been rarer in cultivation in the UK – Wilkinson in his researches for Epitaph for the Elm (1978) had never seen a specimen. In Australia 'Purpurascens' was sold by Searl's Garden Emporium, Sydney at the beginning of the 20th century and was "quite widely" planted in the south-east of the country, where it is said to tolerate dry conditions.[17] Urban plantings include avenue specimens and scattered trees in Fawkner Park, Melbourne.[18][19]

In 2007 the Swedish Biodiversity Centre's 'Programme for Diversity of Cultivated Plants' included 'Purpurascens' (mistakenly called Ulmus procera 'Purpurea') in their plant conservation programme.[20]

Notable trees

Several trees still survive in the UK and Australia. In the UK probably the largest is that in Cottesmore St. Mary's School, Hove, 18 m high, 51 cm d.b.h. (1993).[21] In Edinburgh, six of the seven mature specimens growing in Warriston Cemetery (middle level) were felled in the 1990s; the seventh remains healthy (2014) (height 20 m, bole-girth 2.2 m; labelled 03159 CEM). Ignorance of this cultivar may have occasioned unnecessary felling: the tree's naturally upcurled, greyish foliage in late summer may be mistaken for foliage affected by Dutch elm disease. A vigorous sucker in the cemetery has now become an established tree. In Australia the Avenue of Honour at Wallan, Victoria, was planted solely with 'Purpurascens' in the early 1920s, most of which survive,[22] and the cultivar was also included in the Avenue of Honour in Ballarat in 1918.[23]

Synonymy

Accessions

Europe

Australia

North America

Nurseries

Europe

References

  1. ↑ Koch, K. Dendr. 2 (1), 416 (1872)
  2. ↑ Elwes, H. J. & Henry, A. (1913). The Trees of Great Britain & Ireland. Vol. VII. p. 1868. Private publication, Edinburgh. Republished by Cambridge University Press, 2014.
  3. ↑ Green, P. S. (1964). Registration of cultivar names in Ulmus. Arnoldia, Vol. 24. Arnold Arboretum, Harvard University.
  4. ↑ Elwes, H. J. & Henry, A. (1913). The Trees of Great Britain & Ireland. Vol. VII. p. . Private publication, Edinburgh. Republished by Cambridge University Press, 2014
  5. ↑ Petzold & Kirchner, Arb. Musc. 558 (1864)
  6. 1 2 3 Bean, W. J. (1988) Trees and shrubs hardy in Great Britain, 8th edition, Murray, London.
  7. ↑ www.tradgardsakademin.se
  8. 1 2 Spencer, R., Hawker, J. and Lumley, P. (1991). Elms in Australia. Australia: Royal Botanic Gardens, Melbourne. ISBN 0-7241-9962-4.
  9. ↑ F. J. Fontaine, Dendroflora No.5, (1968)
  10. ↑ Bean, W. J. (1988) Trees and shrubs hardy in Great Britain, 8th edition, Murray, London, p. 640
  11. ↑ Ulmus procera 'Purpurea': Morton Arboretum Catalogue, Accession no. 593–22
  12. ↑ Photograph of newly emerged leaves of 'Purpurea' in Denmark, www.loenbaek.dk
  13. ↑ Emerging 'Purpurea' leaves photographed against sunlight, www.kuningas.ee
  14. ↑ Photograph of 'Purpurea' cuttings, www.kuningas.ee
  15. ↑ Ryston Hall Arboretum catalogue, circa 1920
  16. ↑ E. E. Kemp (Curator, Royal Botanic Garden Edinburgh 1950-71) in After the Elm, eds. Clouston & Stansfield, (London, 1979), p.35
  17. ↑ Spencer, Roger, ed., Horticultural Flora of South-Eastern Australia, Vol. 2 (Sydney, 1995), 111–112
  18. ↑ 'Purpurascens' in Fawkner Park, Melbourne: elsewhere.polydistortion.net
  19. ↑ Spencer, Roger, ed., Horticultural Flora of South-Eastern Australia, Vol. 2 (Sydney, 1995), p. 112
  20. ↑ Leaves and samarae of 'Purpurascens', 'Programme for Diversity of Cultivated Plants', Sweden, pom.info,
  21. 1 2 Johnson, O. (2011). Champion Trees of Britain & Ireland, p. 168. Kew Publishing, Kew, London. ISBN 9781842464526.
  22. ↑ Photographs of 'Purpurascens', Avenue of Honour, Wallan, Victoria: vhd.heritage.vic.gov.au
  23. ↑ ballarat.com
  24. ↑ Elwes, H. J. & Henry, A. (1913). The Trees of Great Britain & Ireland. Vol. VII. p.1868. Private publication, Edinburgh.
  25. ↑ National Elm Collection list www.brighton-hove.gov.uk/index.cfm?request=c1108042
This article is issued from Wikipedia - version of the Tuesday, May 03, 2016. The text is available under the Creative Commons Attribution/Share Alike but additional terms may apply for the media files.