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Elms are deciduous and semi-deciduous trees comprising the flowering plant genus Ulmus in the plant family Ulmaceae. The genus first appeared in the Miocene geological period about 20 million years ago, originating in what is now central Asia. These trees flourished and spread over most of the Northern Hemisphere, inhabiting the temperate and tropical-montane regions of North America and Eurasia, presently ranging southward in the Middle East to Lebanon, and Israel, and across the Equator in the Far East into Indonesia.
The Wych Elm cultivar Ulmus glabra 'Camperdownii', commonly known as the Camperdown Elm, was discovered about 1835–1840 as a young contorted elm growing in the forest at Camperdown House, in Dundee, Scotland, by the Earl of Camperdown's head forester, David Taylor. The young tree was lifted and replanted within the gardens of Camperdown House where it remains to this day. The original tree, which grows on its own roots, is less than 3 m tall, with a weeping habit and contorted branch structure. The earl's gardener is said to have produced the first of what are commonly recognised as Camperdown elms by grafting a cutting to the trunk of a wych elm.
Ulmus rubra, the slippery elm, is a species of elm native to eastern North America, ranging from southeast North Dakota, east to Maine and southern Quebec, south to northernmost Florida, and west to eastern Texas, where it thrives in moist uplands, although it will also grow in dry, intermediate soils. Other common names include red elm, gray elm, soft elm, moose elm, and Indian elm. The tree was first named as part of Ulmus americana in 1753, but identified as a separate species, Ulmus rubra, in 1793 by Pennsylvania botanist Gotthilf Muhlenberg. The slightly later name U. fulva, published by French botanist André Michaux in 1803, is still widely used in dietary-supplement and alternative-medicine information.
Ulmus × hollandica 'Commelin' is a Dutch hybrid cultivar released for sale in 1960. The tree was raised at Baarn as clone 274 by the Foundation Willie Commelin Scholten Phytopathological Laboratory in 1940, from a crossing of Ulmus × hollandica 'Vegeta' and clone 1, an Ulmus minor selected from a 1929 elm seedlings lot obtained from the Barbier nursery, Orléans.
Fine examples around the cathedral in 2007
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 Chinese Elm cultivar Ulmus parvifolia 'UPMTF' was raised by Moon's Tree Farm nursery, Atlanta, United States.
The Chinese Elm cultivar Ulmus parvifolia 'Emer II' or 'Emerald Vase' was cloned from a tree planted circa 1910 on the University of Georgia campus at Athens.
The Chinese Elm cultivar Ulmus parvifolia 'Sempervirens' is an American introduction, commonly known by the synonym 'Evergreen', and may also be in synonymy for U. parvifolia 'Pendens'.
The Siberian Elm cultivar Ulmus pumila 'Park Royal' is a cold-hardy selection raised by the Sheridan Nursery, Toronto, Ontario, Canada.
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 Field Elm cultivar Ulmus minor 'Schuurhoek' was originally an old, nameless clone cultivated c.1880 in the vicinity of Goes, Netherlands, which was taken back into cultivation as 'Schuurhoek' by the van't Westeinde nursery at 's-Heer Abtskerke, Zeeland, in the 1950s. It was identified as U. carpinifolia by Fontaine (1968), though treated as a cultivar of U. × hollandica by some authorities.
The American Elm cultivar Ulmus americana 'Kimley' was cloned by the Sheridan Nurseries, Mississauga, Canada, from a large tree found near Oshawa, Ontario, Canada.
The American Elm cultivar Ulmus americana 'Minneapolis Park' was a selection made by the Minneapolis Park Department as being particularly suited to boulevard planting.
The Siberian Elm cultivar Ulmus pumila 'Pendula' is from northern China, where it is known as Lung chao yü shu. It was classified by Frank Meyer in Fengtai in 1908, and introduced to the United States by him from the Peking Botanical Garden as Weeping Chinese Elm. The USDA plant inventory record (1916) noted that it was a "rare variety even in China". It was confirmed as an U. pumila cultivar by Krüssmann (1962).
The hybrid elm cultivar Ulmus × intermedia 'Rosehill' is an American hybrid cultivar originally raised by the Rose Hill Nurseries of Kansas City, Missouri, from a selection of Ulmus pumila × Ulmus rubra seedlings made in 1951.
The Chinese Elm cultivar Ulmus parvifolia 'Pendens' was listed by Rehder in Journal of the Arnold Arboretum 26: 473, 1872 as Ulmus parvifolia f. pendens.
The Field Elm cultivar Ulmus minor 'Rugosa' was distributed by the Späth nursery, Berlin, in the 1890s and early 1900s as U. campestris rugosaKirchner. Kirchner's tree, like Späth's a level-branched suberose field elm, was received from Belgium in 1864 as Ulmus rugosa pendula. Kirchner stressed that it was different from Loudon's Ulmus montana var. rugosa, being "more likely to belong to U. campestris or its subspecies, the Cork-elm".
The Field Elm cultivar Ulmus minor 'Suberosa', commonly known as the Cork-barked elm, is a slow-growing or dwarf form of conspicuously suberose Field Elm. Of disputed status, it is considered a distinct variety by some botanists, among them Henry (1913), Krüssmann (1984), and Bean (1988), and is sometimes cloned and planted as a cultivar. Henry said the tree "appears to be a common variety in the forests of central Europe", Bean noting that it "occurs in dry habitats". By the proposed rule that known or suspected clones of U. minor, once cultivated and named, should be treated as cultivars, the tree would be designated U. minor 'Suberosa'. The Späth nursery of Berlin distributed an U. campestris suberosa alataKirchn. [:'corky-winged'] from the 1890s to the 1930s.
The elm cultivar UlmusDensa was described from specimens growing near Ashkabad as U. densaLitv. in Schedae ad Herbarium Florae Rossicae (1908). Litvinov, reporting it growing wild in the mountains of Turkestan, Ferghana, and Aksu, as well as in cultivation, considered it a species, a view upheld by the Soviet publications Trees and Shrubs in the USSR (1951) and Flora of Armenia (1962), and by some current plant lists. Other authorities take it to be a form of U minor, distinctive only in its dense crown and upright branching. The Moscow State University herbarium gives (2020) Ulmus minor as the "accepted name" of U. densaLitv..
References
- ↑ Green, Peter Shaw (1964). "Registration of cultivar names in Ulmus". Arnoldia. Arnold Arboretum, Harvard University. 24 (6–8): 41–80. Retrieved 16 February 2017.
- ↑ Bateman, Chris (November 15, 2014). "How Toronto got its various nickname". blogTO. Retrieved October 23, 2017.