''Ulmus'' 'Clusius' is a Dutch

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 Elms are deciduous and semi-deciduous trees comprising the flowering plant genus ''Ulmus'' in the plant family Ulmaceae. They are distributed over most of the Northern Hemisphere, inhabiting the temperate and tropical-montane regions of North ...

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 ...

raised at the Dorschkamp Research Institute for Forestry & Landscape Planning,

Wageningen Wageningen () is a municipality and a historic city in the central Netherlands, in the province of Gelderland. It is famous for Wageningen University, which specialises in life sciences. The municipality had a population of in , of which many ...

, and released to commerce in 1983. 'Clusius' was derived from a crossing of the same Dutch clones that produced the fastigiate 'Lobel' released in 1973: '202' ( 'Exoniensis' × ''U. wallichiana'') and '336' ( 'Bea Schwarz' selfed).

Description

The tree has a broader crown than its siblings', whilst the generally

obovate The following is a list of terms which are used to describe leaf morphology in the description and taxonomy of plants. Leaves may be simple (a single leaf blade or lamina) or compound (with several leaflets). The edge of the leaf may be regular ...

leaves, < 11 cm long by 7 cm wide, are less acuminate at the apex. Like 'Lobel', the tree flushes markedly later than most other elms, and is rarely in full leaf before mid-May.

Pests and diseases

Whilst the resistance of 'Clusius' 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 ...

proved marginally greater than that of its Dutch predecessors, rated 4 out of 5,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. it has been eclipsed by later developments such as . Consequently, sales in the Netherlands declined from over 8,000 in 1979 to 600 in 2004.

Cultivation

While 'Clusius' remains for sale in Europe, its planting where the disease remains prevalent cannot be recommended. 'Clusius' featured in New Zealand government trials during the 1990s at the Hortresearch station,

Palmerston North Palmerston North (; mi, Te Papa-i-Oea, known colloquially as Palmy) is a city in the North Island of New Zealand and the seat of the Manawatū-Whanganui region. Located in the eastern Manawatu Plains, the city is near the north bank of the ...

, but is not known to have been introduced to North America.

Etymology

The cultivar is named for

Carolus Clusius Charles de l'Écluse, L'Escluse, or Carolus Clusius (19 February 1526 – 4 April 1609), seigneur de Watènes, was an Artois doctor and pioneering botanist, perhaps the most influential of all 16th-century scientific horticulturists. Life Clu ...

, a Dutch naturalist of the

Renaissance The Renaissance ( , ) , from , with the same meanings. is a period in European history The history of Europe is traditionally divided into four time periods: prehistoric Europe (prior to about 800 BC), classical antiquity (800 BC to AD ...

Accessions

;Europe * Arboretum de La Petite Loiteriebr>

Monthodon Monthodon () is a commune in the Indre-et-Loire department in central France. Population Sights * Arboretum de la Petite Loiterie See also *Communes of the Indre-et-Loire department The following is a list of the 272 communes of the Indre- ...

, France. No details available *

Grange Farm Arboretum The Grange Farm Arboretum is a small private arboretum comprising 3 hectares accommodating over 800 trees, mostly native and ornamental species or cultivars, notably oaks, ashes, walnuts and elms, growing on a calcareous loam.Ostler, J. (2009) ...

Sutton St James Sutton St James is a village and civil parish in the South Holland district of Lincolnshire, England, about south-west of Long Sutton. Lying in the Lincolnshire Fens, Sutton St James did not exist at the time of the 1086 ''Domesday Book''. Su ...

, Spalding, Lincs., UK. Acc. no. 817. * Sir Harold Hillier Gardens,

Ampfield Ampfield is a village and civil parish in the Borough of Test Valley in Hampshire, England, between Romsey, Eastleigh, and Winchester. It had a population at the 2001 census of 1,474, increasing to 1,583 at the 2011 Census. Geography Ampfield ...

, Romsey,

Hampshire Hampshire (, ; abbreviated to Hants) is a ceremonial and non-metropolitan county in western South East England on the coast of the English Channel. Home to two major English cities on its south coast, Southampton and Portsmouth, Hampshire ...

, UK. Acc. no: 2019.0441 * Wijdemeren City Council, Netherlands. Elm Collection. planted mainly in Kortenhoef since 2006.

Nurseries

*Noordplan

Glimmen Glimmen is a village in the northeastern Netherlands. It is located in the municipality of Groningen, about 10 kilometres from the city. It had a population of around 1,342 in 2021. The river Drentsche Aa flows past the village, nearby the ''Huis ...

, Netherlands.

References

{{Elm species, varieties, hybrids, hybrid cultivars and species cultivars , state=collapsed Hybrid elm cultivar Ulmus articles with images Ulmus