Ulmus 'Purpurea'

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

The elm cultivar '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 (:procera) var. purpurea Petz. & Kirchn.,^[2][4] 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',^[5] 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.^[6] 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',^[7] the name given by F. J. Fontaine to 'Purpurea'.^[8][9] An elm obtained in 1922 from H. Kohankie & Son was listed by the Morton Arboretum, Illinois, as Ulmus procera 'Purpurea',^[10] 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 straggling, irregular, open ascending branches; the bark has a reddish-brown hue. The tree has slightly folded, dark-green leaves (the darkest green of all the elms) which, like the shoots, have a brief dark-purple flush in spring.^[11][12][13] Prior to flushing, the leaf-buds are long, sharply pointed, and dark purple. The flowers, too, emerge a uniform dark purple. The fruit, tinged purple, is small and intermediate between glabra and minor. After the spring purple flush, the leaves become olive green then darken in the summer. Their underside remains paler. The leaves' increasing fold as the year progresses gives the foliage a greyish hue later.^[7]

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^[14] 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.^[15] 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.^[16] Urban plantings include avenue specimens and scattered trees in Fawkner Park, Melbourne.^[17][18]

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.^[19]

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, 18m high, 51 cm d.b.h. (1993).^[20] 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,^[21] and the cultivar was also included in the Avenue of Honour in Ballarat in 1918.^[22]

Synonymy

• Ulmus montana (: glabra) var. atropurpurea: Elwes and Henry^[2]
• Ulmus montana (: glabra) 'Purpurea': Kew Garden list of names^[5]
• Ulmus 'Purpurea': Koch ; Bean;^[5] National Elm Collection elm list^[23]
• Ulmus x hollandica 'Purpurascens': Fontaine, Dendroflora No.5 (1968)
• ?Ulmus campestris (: minor) 'Purpurea': Kirchner
• ?Ulmus procera 'Purpurea': Morton Arboretum Catalogue 2006.

Accessions

Europe

• Brighton & Hove City Council, UK, NCCPG elm collection . UK champion: Cottesmore St. Mary's School, Hove, 18m high, 51 cm d.b.h. in 1993.^[20]
• RBG Wakehurst Place, UK. Listed as U. glabra 'Atropurpurea'. Acc. no. 1896-1411.
• Grange Farm Arboretum, Sutton St. James, Spalding, Lincolnshire, UK.

Australia

• Avenue of Honour, Wallan, Victoria.
• Avenue of Honour, Ballarat, Victoria.

North America

• Dominion Arboretum, Ottawa, Canada. No acc. details.

Nurseries

Europe

• Loenbaek Planteskole , Holstebro, Denmark
• Propagation Nurseries Vermeerderingstuin Horst and Zeewolde, Netherlands

References