The
Field Elm
''Ulmus minor'' Mill., the field elm, is by far the most polymorphic of the European species, although its taxonomy remains a matter of contention. Its natural range is predominantly south European, extending to Asia Minor and Iran; its northern ...
cultivar ''Ulmus minor'' 'Retiro' was raised from seed collected in 2002 from a tree growing in the
El Retiro park (),
in the centre of Madrid by researchers at the Escuela Técnica Superior de Ingenieros de Montes,
Universidad Politėcnica de Madrid
The Technical University of Madrid or sometimes called Polytechnic University of Madrid ( es, Universidad Politécnica de Madrid, UPM) is a public university, located in Madrid, Spain. It was founded in 1971 as the result of merging different Te ...
.
'Retiro' was introduced to the UK in 2015, by Hampshire & Isle of Wight Branch,
Butterfly Conservation
Butterfly Conservation (BC) is a UK-wide nonprofit environmentalist organization and charity dedicated to conserving butterflies, moths, and the environment. The charity uses its research to provide advice on how to conserve and restore butterfly ...
, as part of an assessment of
DED-resistant cultivars as potential hosts of the endangered
White-letter Hairstreak.
[Brookes, A. H. (2022). ''Great Fontley Elm Trial, 2022 Report''. Butterfly Conservation, Lulworth, England.]
Description
'Retiro' grew at a comparatively modest rate of 70 cm per annum in the trials at Puerta de Hierro, Madrid. The erect branches, devoid of corky tissue, form a globular crown. The leaves, on 7 mm
petioles, are
elliptic, typically acuminate at the apex, the average length and width 71 × 42 mm, the margins doubly serrate. Foliar density relative to 'Sapporo Autumn Gold' is described as 'high'. In the Madrid study, the appearance of the tree was rated 4 / 5.
[ The tree begins leafing in mid April (week 15) in southern England, where it also began suckering from roots, the first of the Madrid ''U. minor'' clones to do so, at age 7; flowering began at age 9.][
File:Ulmus minor 'Retiro' leaf.jpg, 'Retiro' leaf
File:Ulmus minor 'Retiro' , exhibiting characteristic arching stem.jpg, 'Retiro' sapling, with typical arching stem
File:Retiro root suckering 1.jpg, 'Retiro' root suckering, Boarhunt, UK, age 7
]
Pests and diseases
'Retiro' is one of a number found to have a very high resistance to Dutch Elm Disease, on a par with, if not greater than, the 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 ...
cultivar 'Sapporo Autumn Gold'.[
]
Cultivation
The cultivar is (2018) undergoing further trials in a different environment in Spain, where it was tested by inoculation in 2016. If resistance is still considered satisfactory, the tree will be released to commerce under licence. 'Retiro' is also being assessed as part of Butterfly Conservation's elm trials in southern Hampshire, England, where it was easily propagated from hardwood cuttings .[
]
Accessions
Europe
* Grange Farm Arboretum, Lincolnshire, UK. Acc. no. 1269.
* Great Fontley Butterfly Conservation Elm Trials plantation, UK. One sapling planted 2015.
References
{{Elm species, varieties, hybrids, hybrid cultivars and species cultivars , state=collapsed
Field elm cultivar
Ulmus articles with images
Ulmus
Technical University of Madrid elm clones