| Ulmus laevis 'Helena' | |
|---|---|
| Species | Ulmus laevis |
| Cultivar | 'Helena' |
| Origin | Europe |
The European White Elm cultivar Ulmus laevis 'Helena' is a Dutch introduction in commerce circa 2010 at the Boomkwekerij s'Herenland at Randwijk (PBR applied for: EU 20142249). [1] The cultivar was cloned from a tree planted as one of a line of 17 White Elms at Eibergen circa 1900, which developed a straight central leader.
The tree is described as having upright, uniform, growth, producing yellow leaves in autumn. At age 100, 'Helena' should be approximately 22 m high, with a crown diameter of about 12 m. [1]
'Helena' is judged 'sustainable and durable in public parks', [1] but has not been planted beyond the Netherlands (2016).
None known
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 America and Europe, where it has devastated native populations of elms that did not have resistance to the disease. It has also reached New Zealand. The name "Dutch elm disease" refers to its identification in 1921 and later in the Netherlands by Dutch phytopathologists Bea Schwarz and Christine Buisman, who both worked with Professor Johanna Westerdijk. The disease affects species in the genera Ulmus and Zelkova; therefore it is not specific to the Dutch elm hybrid.
Ulmus laevisPall., variously known as the European white elm, fluttering elm, spreading elm, stately elm and, in the United States, the Russian elm, is a large deciduous tree native to Europe, from France northeast to southern Finland, east beyond the Urals into Kyrgyzstan and Kazakhstan, and southeast to Bulgaria and the Crimea; there are also disjunct populations in the Caucasus and Spain, the latter now considered a relict population rather than an introduction by man, and possibly the origin of the European population. U. laevis is rare in the UK, although its random distribution, together with the absence of any record of its introduction, has led at least one British authority to consider it native. NB: The epithet 'white' elm commonly used by British foresters alluded to the timber of the wych elm.
Ulmus chenmouiW. C. Cheng, commonly known as the Chenmou, or Langya Mountain elm, is a small deciduous tree from the more temperate provinces of Anhui and Jiangsu in eastern China, where it is found at elevations below 200 m on the Langya Shan and Baohua Shan mountains. The tree was unknown in the West until 1979, when seeds were sent from Beijing to the De Dorschkamp research institute at Wageningen in the Netherlands.
The Field Elm cultivar Ulmus minor 'Sarniensis', known variously as Guernsey Elm, Jersey Elm, Wheatley Elm, or Southampton Elm, was first described by MacCulloch in 1815 from trees on Guernsey, and was planted in the Royal Horticultural Society's gardens in the 1820s. It was listed in the Loddiges catalogue of 1836 as Ulmus sarniensis and by Loudon in Hortus lignosus londinensis (1838) as U. campestris var. sarniensis. The origin of the tree remains obscure; Richens believed it "a mutant of a French population of Field elm", noting that "elms of similar leaf-form occur in Cotentin and in northern Brittany. They vary much in habit but some have a tendency to pyramidal growth. Whether the distinctive habit first developed on the mainland or in Guernsey is uncertain."
The Dutch hybrid elm cultivar Ulmus × hollandica 'Groeneveld' was cloned in 1949 at the De Dorschkamp Institute, Wageningen, and released in 1963 in response to the earlier, less virulent form of Dutch elm disease that afflicted Europe shortly after the First World War. The cultivar was derived from a crossing of Dutch clones '49', and '1', a Field Elm Ulmus minor found in central France and marketed by the Barbier nursery in Orléans.
The hybrid elm cultivar Ulmus × hollandica 'Belgica', one of a number of hybrids arising from the crossing of Wych Elm with a variety of Field Elm, was reputedly raised in the nurseries of the Abbey of the Dunes, Veurne, in 1694. Popular throughout Belgium and the Netherlands in the 19th century both as an ornamental and as a shelter-belt tree, it was the 'Hollandse iep' in these countries, as distinct from the tree known as 'Dutch Elm' in Great Britain and Ireland since the 17th century: Ulmus × hollandica 'Major'. In Francophone Belgium it was known as orme gras de Malines.
Ulmus 'Wanoux' is a Dutch hybrid cultivar raised at the Dorschkamp Research Institute for Forestry & Landscape Planning, Wageningen, from an open pollination of 'Plantyn'. Originally identified as clone No. 762, it was selected for assessment by the French Institut National de la Recherche Agronomique (INRA), which patented it as 'Wanoux' in 2006.
Ulmus 'Columella' is a Dutch elm cultivar raised by the Dorschkamp Research Institute for Forestry & Landscape Planning, Wageningen, from a selfed or openly pollinated seedling of the hybrid clone '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 pathogen, Ophiostoma novo-ulmi. However, propagated by grafting onto Wych Elm rootstocks, graft failure owing to incompatibility has become a common occurrence in the Netherlands.
The Field Elm cultivar Ulmus minor 'Christine Buisman' was the first cultivar released by the Dutch elm breeding programme, initiated in response to the less virulent form of Dutch elm disease (DED), Ophiostoma ulmi, which afflicted Europe's elms after the First World War. 'Christine Buisman' was selected from a batch of 390 seedlings grown from seed collected in the Parque de la Quinta de la Fuente del Berro, Madrid, by Mrs Van Eeghen, a friend of elm researcher Johanna Westerdijk, in 1929 and named for the elm disease researcher Christine Buisman. Originally identified as Ulmus foliacea, it was later treated as Ulmus × hollandica by Melville. However, more recent research in Belgium using DNA markers has reaffirmed 'Christine Buisman' as a clone of U. minor.
The hybrid elm cultivar Ulmus 'Den Haag' is a Dutch development derived from a chance crossing of the Siberian Elm cultivar Ulmus pumila 'Pinnato-ramosa' and the Belgian Elm Ulmus × hollandica 'Belgica'. S. G. A. Doorenbos (1891-1980), Director of Public Parks in The Hague, finding that seeds he had sown in 1936 from the Zuiderpark 'Pinnato-ramosa' had hybridized with the local 'Belgica', selected six for trials. The best was cloned and grafted on 'Belgica' rootstock as 'Den Haag'; it was planted first in that city, then released to nurseries elsewhere in the Netherlands. The other five were also planted in The Hague.
The dwarf wych elm cultivar Ulmus glabra 'Nana', a very slow growing shrub that with time forms a small tree, is of unknown origin. It was listed in the Simon-Louis 1869 catalogue as Ulmus montana nana. Henry (1913), referring his readers to an account of the Kew specimen in the journal Woods and Forests, 1884, suggested that it may have originated from a witch's broom. It is usually classified as a form of Ulmus glabra and is known widely as the 'Dwarf Wych Elm'. However, the ancestry of 'Nana' has been disputed in more recent years, Melville considering the specimen once grown at Kew to have been a cultivar of Ulmus × hollandica.
The European White Elm cultivar Ulmus laevis 'Colorans' was listed as U. effusa var. colorans by Kirchner in Petzold & Kirchner, Arboretum Muscaviense (1864).
The European White Elm cultivar Ulmus laevis 'Ornata' was erroneously identified by Carrière as U. communis ornata in 1858. 'Ornata' was named by Carrière for the numerous and intensely green leaves which gave the trees 'a magnificent appearance'.
Ulmus laevis var. celtideaRogow. is a putative variety of European White Elm first described by Rogowicz, who found the tree in 1856 along the river Dnjepr near Chernihiv in what is now northern Ukraine. The type specimen is held at the National Herbarium of Ukraine. The variety was first named as Ulmus pedunculata var. celtidea. Litvinov (1908) considered it a species, calling it Ulmus celtideaLitv., a view not upheld by other authorities.
Ulmus 'Louis van Houtte' is believed to have been first cultivated in Ghent, Belgium circa 1863. It was first mentioned by Franz Deegen in 1886. It was once thought a cultivar of English Elm Ulmus minor 'Atinia', though this derivation has long been questioned; W. J. Bean called it "an elm of uncertain status". Its dissimilarity from the type and its Belgian provenance make the 'Atinia' attribution unlikely. Fontaine (1968) considered it probably a form of U. × hollandica.
Ulmus 'Arno' is an Italian hybrid cultivar derived from a crossing of 'Plantyn' with the Siberian Elm Ulmus pumila clone S.2. It was raised by the Istituto per la Protezione delle Piante (IPP) in Florence, and released in 2007. However, 'Arno' was not a commercial success; propagation had ceased by 2010, and it is no longer patent protected.
Ulmus 'Fiorente' is a hybrid cultivar elm derived from a crossing of the Siberian Elm Ulmus pumila clone 'S.10' from Lucca, Italy, with the Ulmus minor clone 'C.02' from Lungarno, Florence, by the Istituto per la Protezione delle Piante (IPP), part of the Italian National Research Council, in Florence. 'Fiorente' was patented in 2006, and released to commerce in 2012.
The European White Elm cultivar Ulmus laevis 'Urticifolia' known as the Nettle Leaved Elm was raised by Jacques as a chance seedling in 1830, and propagated by grafting. It was later mentioned by de Vries in 1906.
The Ulmus pumila cultivar 'Aurescens' was introduced by Georg Dieck at the National Arboretum, Zöschen, Germany, circa 1885. Dieck grew the tree from seed collected in the Ili valley, Turkestan by the lawyer and amateur naturalist Vladislav E. Niedzwiecki while in exile there. Dieck originally named the tree U. pinnato-ramosaf.aurescens.
The field elm cultivar 'Punctata' ['spotted', the leaf] first appeared in the 1886–87 catalogue of Simon-Louis of Metz, France, as U. campestris punctata. It was distributed by the Späth nursery, Berlin, in the 1890s and early 1900s as U. campestris punctataSim.-Louis, the Späth catalogue listing it separately from U. campestris fol. argenteo-variegata and from U. campestris fol. argenteo-marginata. Green considered it possibly a synonym of the Field Elm cultivar 'Argenteo-Variegata'.
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