Ulmus 'Columella'

Ulmus hybrid
'Columella', Amsterdam. Photo: Ronnie Nijboer, Bonte Hoek kwekerijen.
Details
Hybrid parentage	'Plantyn', selfed
Cultivar	'Columella'
Origin	Wageningen, The Netherlands

Ulmus 'Columella' is a Dutch cultivar raised by the Dorschkamp Research Institute in Wageningen from a selfed seedling of the hybrid 'Plantyn' sown in 1967. It was released for sale in 1989 after proving extremely resistant to Dutch elm disease following inoculation with unnaturally high doses of the causative fungus Ophiostoma novo-ulmi ^[1].

Description

'Columella' makes a tall, fastigiate tree with very upright branches, but broadens in later years [2] [3]. The rough, rounded, and curiously twisted leaves, < 7 cm long, are the result of a recessive gene inherited from its Exeter Elm ancestor, and are arranged in asymmetric clusters on short branchlets. The samarae, broadly obovate, are 13-17 mm long by 10-12 mm wide.

• 
• 
• 

Pests and diseases

Rated 5 out of 5 ^[2] 'Columella' has a very high resistance to Dutch elm disease.

Cultivation

Wind resistant, the tree has been planted throughout the Netherlands, where its columnar shape has made it popular as a street tree. It is commonly found in Amsterdam, where it has been widely planted as a replacement for the similarly-fastigiate Guernsey Elm, U. minor subsp. sarniensis [4], itself a replacement for the Belgian Elm, Ulmus × hollandica 'Belgica', which had succumbed so readily to the earlier strain of Dutch elm diease after World War I.

In trials conducted by Butterfly Conservation in southern Hampshire, England, 'Columella' was the only cultivar to become distressed during the drought of 2006, shedding most of its foliage by early August; a trait possibly inherited from one of the tree's ancestors, the Himalayan Elm Ulmus wallichiana; several trees later died. 'Columella' first flowered aged 8 years, in March; the resultant seeds were found to have a moderate viability ^[3]. 'Columella' featured in New Zealand government trials during the 1990s at the Hortresearch station, Palmerston North, but is not known to have been introduced to North America.

Hybrid cultivars

• Clone FL 666 (Heybroek's 405* × 'Columella'), Istituto per la Protezione delle Piante, Florence. Not in commerce. *(U. × hollandica × U. minor)
• Clone FL 589 ('San Zanobi' × 'Columella'), Istituto per la Protezione delle Piante, Florence. Not in commerce.

Etymology

The hybrid is named for the Roman agronomist Columella, who introduced the Atinian elm (now more commonly known as the English Elm) to Spain from Italy circa AD 50.

Accessions

Europe

• Arboretum de La Petite Loiterie [5], Monthodon, France. No details available.
• Grange Farm Arboretum, Sutton St James, Spalding, Lincs., UK. Acc. no. 818.
• Great Fontley Farm, Fareham, UK, Butterfly Conservation Elm Trials plantation, Home Field I6, (planted 2003).
• Brighton & Hove City Council, UK, NCCPG elm collection [6]. East Drive, Queen's Park.

Nurseries

Europe

• Boomwekerijen 'De Batterijen' [7], Ochten, Netherlands
• J A Jones [8], Southport, Lancashire, UK
• Hilliers Nurseries [9], Ampfield, UK. Standards only.
• PlantenTuin Esveld [10], Boskoop, Netherlands
• Tuinenlandschap [11], Doetinchem, The Netherlands
• UmbraFlor [12], Spello, Italy
• Westerveld Boomkwekerij B.V.[13], Opheusden, Netherlands
• Boomkwekerij 't Herenland[14], Randwijk, Netherlands

References

1. ^ Heybroek, H. (1993). The Dutch Elm Breeding Program. In Sticklen & Sherald (Eds.) (1993). Dutch Elm Disease Research, Chapter 3. Springer Verlag, New York, USA.
2. ^ Heybroek, H. M., Goudzwaard, L, Kaljee, H. (2009). Iep of olm, karakterboom van de Lage Landen (:Elm, a tree with character of the Low Countries). KNNV, Uitgeverij. ISBN 9709050112819
3. ^ Brookes, A. H. (2010). Disease-resistant elm cultivars: Butterfly Conservation trials report, 2010. Butterfly Conservation, Hants & IoW Branch, England. [1]