|Siberian elms in the Gobi Desert of Mongolia|
Ulmus pumila, the Siberian elm, is a tree native to Central Asia, eastern Siberia, the Russian Far East, Mongolia, Tibet, northern China, India (northern Kashmir) and Korea.It is also known as the Asiatic elm and dwarf elm, but sometimes miscalled the 'Chinese Elm' ( Ulmus parvifolia ). It is the last tree species encountered in the semi-desert regions of central Asia. Described by Pallas in the 18th century from specimens from Transbaikal, Ulmus pumila has been widely cultivated throughout Asia, North America, Argentina, and southern Europe, becoming naturalized in many places, notably across much of the United States.
The Siberian elm is usually a small to medium-sized, often bushy, deciduous tree growing to 25 m tall, the d.b.h. to 1 m; the bark is dark gray, irregularly longitudinally fissured. The branchlets are yellowish gray, glabrous or pubescent, unwinged and without a corky layer, with scattered lenticels. The winter buds dark brown to red-brown, globose to ovoid. The petiole is 4–10 mm, pubescent, the leaf blade elliptic-ovate to elliptic-lanceolate, 2-8 × 1.2-3.5 cm, the colour changing from dark green to yellow in autumn. The perfect, apetalous wind-pollinated flowers bloom for one week in early spring, before the leaves emerge, in tight fascicles (bundles) on last year's branchlets. However, flowers emerging in early February are often damaged by frost, consequently the species was dropped from the Dutch elm breeding programme. Each flower is about 3 mm across and has a green calyx with 4–5 lobes, 4–8 stamens with brownish-red anthers, and a green pistil with a two-lobed style. Unlike most elms, the Siberian elm is able to self-pollinate successfully.
The wind-dispersed samarae are whitish tan, orbicular to rarely broadly obovate or elliptical, 1-2 × 1-1.5 cm, glabrous except for pubescence on stigmatic surface; the stalk 1–2 mm, the perianth persistent. The seed is at centre of the samara or occasionally slightly toward apex but not reaching the apical notch. Flowering and fruiting occur March to May. Ploidy: 2n = 28. The tree also suckers readily from its roots.
The tree is short-lived in temperate climates, rarely reaching more than 60 years of age, but in its native environment may live to between 100 and 150 years. km southeast of Khanbogt in the south Gobi, with a girth of 5.55 m in 2009, may exceed 250 years (based on average annual ring widths of other U. pumila in the area).[ citation needed ]A giant specimen, 45
The tree has considerable variability in resistance to Dutch elm disease; for example, trees from north-western and north-eastern China exhibit significantly higher tolerance than those from central and southern China.Moreover, it is highly susceptible to damage from many insects and parasites, including the elm leaf beetle Xanthogaleruca luteola , the Asian 'zigzag' sawfly Aproceros leucopoda , Elm Yellows, powdery mildew, cankers, aphids, leaf spot and, in the Netherlands, coral spot fungus Nectria cinnabarina . However, U. pumila is the most resistant of all the elms to verticillium wilt.
U. pumila was introduced into Spain as an ornamental, probably during the reign of Philip II (1556–98),and from the 1930s into Italy. In these countries it has naturally hybridized with the Field Elm U. minor (see below). In Italy it was widely used in viniculture, notably in the Po valley, to support the grape vines until the 1950s, when the demands of mechanization made it unsuitable.
Three specimens were supplied by the Späth nursery of Berlin to the Royal Botanic Garden Edinburgh in 1902 as U. pumila, [ citation needed ]in addition to specimens of the narrow-leaved U. pumila cultivar 'Pinnato-ramosa' (see 'Cultivars' below). One was planted in RBGE; the two not planted in the Garden may survive in Edinburgh, as it was the practice of the Garden to distribute trees about the city. Kew Gardens obtained specimens of U. pumila from the Arnold Arboretum in 1908 and, as U. pekinensis, via the Veitch Nurseries in 1910 from William Purdom in northern China. A specimen obtained from Späth and planted in 1914 stood in the Ryston Hall arboretum, Norfolk, in the early 20th century. The tree was propagated and marketed by the Hillier & Sons nursery, Winchester, Hampshire, from 1962 to 1977, during which time over 500 were sold. More recently, the popularity of U. pumila in the Great Britain has been almost exclusively as a bonsai subject, and mature trees are largely restricted to arboreta.
U. pumila is said to have been introduced to the United States in 1905 by Prof. J. G. Jack, [ citation needed ]and later by Meyer, though 'Siberian elm' appears in some 19th-century US nursery catalogues. The tree was cultivated at the USDA Experimental Station at Mandan, North Dakota, where it flourished. It was consequently selected by the USDA for planting in shelter belts across the prairies in the aftermath of the Dustbowl disasters, where its rapid growth and tolerance for drought and cold initially made it a great success. However, the species later proved susceptible to numerous maladies. Attempts to find a more suitable cultivar were initiated in 1997 by the Plant Materials Center of the USDA, which established experimental plantations at Akron, Colorado, and Sidney, Nebraska. The study, no. 201041K, will conclude in 2020.
The seeds lose their viability rapidly after maturity unless placed on suitable germination conditions or dried and placed at low temperatures.The species has a high sunlight requirement and is not shade-tolerant; with adequate light it exhibits rapid growth. The tree is also fairly intolerant of wet ground conditions, growing better on well-drained soils. While it is very resistant to drought and severe cold, and able to grow on poor soils, its short period of dormancy, flowering early in spring followed by continuous growth until the first frosts of autumn, renders it vulnerable to frost damage.
As an ornamental U. pumila is a very poor tree, tending to be short-lived, with brittle wood and poor crown shape, but it has nevertheless enjoyed some popularity owing to its rapid growth and provision of shade. The Siberian Elm has been described as "one of the world's worst... ornamental trees that does not deserve to be planted anywhere".Yet in the US during the 1950s, the tree was also widely promoted as a fast-growing hedging substitute for privet, and as a consequence is now commonly found in nearly all states.
The unripe seeds have long been eaten by the peoples of Manchuria, and during the Great Chinese Famine they also became one of the most important foodstuffs in the Harbin region. The leaves were also gathered, to the detriment of the trees, prompting a prohibition order by the authorities, which was largely ignored. The leaves eaten raw are not very palatable, but stewed and prepared with Kaoliang or Foxtail millet make a better tasting and more filling meal.
In North America, Ulmus pumila has become an invasive species in much of the region from central Mexiconorthward across the eastern and central United States to Ontario, Canada. It also hybridizes in the wild with the native U. rubra (Slippery Elm) in the central United States, prompting conservation concerns for the latter species. In South America, the tree has spread across much of the Argentine pampas
In Europe it has spread widely in Spain, and hybridizes extensively there with the native field elm (U. minor),contributing to conservation concerns for the latter species. Research is ongoing into the extent of hybridisation with U. minor in Italy.
Ulmus pumila is often found in abundance along railroads and in abandoned lots and on disturbed ground. The gravel along railroad beds provides ideal conditions for its growth: well-drained, nutrient poor soil, and high light conditions; these beds provide corridors which facilitate its spread. Owing to its high sunlight requirements, it seldom invades mature forests, and is primarily a problem in cities and open areas,as well as along transportation corridors.
The species is now listed in Japan as an alien species recognized as established in Japan or found in the Japanese wild.
Two varieties were traditionally recognized: var. pumila and var. arborea, the latter now treated as a cultivar, U. pumila 'Pinnato-ramosa'.
Valued for the high resistance of some clones to Dutch elm disease, over a dozen selections have been made to produce hardy ornamental cultivars, although several may no longer be in cultivation:
Some authorities consider the cultivar 'Berardii' a form of Ulmus pumila.For the 19th-century cultivar called 'Siberian elm' by Castle Nurseries, Nottingham, see 'Nottingham elm'.
The species has been widely hybridized in the United States and Italy to create robust trees of more native appearance with high levels of resistance to Dutch elm disease:
Roerich describes a specimen discovered on his travels through Mongolia:
The US National Champion, measuring 33.5 m (109 ft 11 in) high in 2011, grows in Berrien County, Michigan. In the UK the TROBI Champions grow at Thorp Perrow Arboretum, Yorkshire, 19 m (62 ft 4 in) × 70 cm (2 ft 4 in) in 2004, and at St Ann's Well Gardens, Hove, Sussex 20 m (65 ft 7 in) × 60 cm (2 ft 0 in) in 2009.
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 wallichianaPlanch., the Himalayan elm, also known as the Kashmir elm and Bhutan elm, is a mountain tree ranging from central Nuristan in Afghanistan, through northern Pakistan and northern India to western Nepal at elevations of 800–3000 m. Although dissimilar in appearance, its common name is occasionally used in error for the cherry bark elm Ulmus villosa, which is also endemic to the Kashmir, but inhabits the valleys, not the mountain slopes. The species is closely related to the wych elm U. glabra.
Ulmus davidiana var. japonica, the Japanese elm, is one of the larger and more graceful Asiatic elms, endemic to much of continental northeast Asia and Japan, where it grows in swamp forest on young alluvial soils, although much of this habitat has now been lost to intensive rice cultivation.
Ulmus minorMill., 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 outposts are the Baltic islands of Öland and Gotland, although it may have been introduced here by man. The tree's typical habitat is low-lying forest along the main rivers, growing in association with oak and ash, where it tolerates summer floods as well as droughts.
Ulmus castaneifoliaHemsley, the chestnut-leafed elm or multinerved elm, is a small deciduous tree found across much of China in broadleaved forests at elevations of 500–1,600 metres (1,600–5,200 ft).
Ulmus laciniata(Trautv.) Mayr, known variously as the Manchurian, cut-leaf, or lobed elm, is a deciduous tree native to the humid ravine forests of Japan, Korea, northern China, eastern Siberia and Sakhalin, growing alongside Cerciphyllum japonicum, Aesculus turbinata, and Pterocarya rhoifolia, at elevations of 700–2200 m, though sometimes lower in more northern latitudes, notably in Hokkaido.
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.
Ulmus 'Homestead' is an American hybrid elm cultivar raised by Alden Townsend of the United States National Arboretum at the Nursery Crops Laboratory in Delaware, Ohio. The cultivar arose from a 1970 crossing of the Siberian Elm Ulmus pumila with the hybrid N 215, the latter grown from seed sent in 1960 to the University of Wisconsin-Madison elm breeding team by Hans Heybroek of the De Dorschkamp Research Institute in the Netherlands. Tested in the US National Elm Trial coordinated by Colorado State University, 'Homestead' averaged a survival rate of 85% after 10 years. 'Homestead' was released to commerce without patent restrictions in 1984.
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 'Morton' is an elm cultivar cloned from a putative intraspecific hybrid planted at the Morton Arboretum in 1924, which itself originated as seed collected from a tree at the Arnold Arboretum in Massachusetts. Although this tree was originally identified as Ulmus crassifolia, it is now believed to have been a hybrid of the Japanese elm and Wilson's elm. Accolade has proven to be the most successful cultivar tested in the US National Elm Trial, averaging a survival rate of 92.5% overall.
The Japanese elm cultivar Ulmus davidianavar.japonica 'Prospector' was originally treated as a cultivar of Wilson's elm U. wilsonianaSchneid., a species sunk as Ulmus davidiana var. japonica by Fu. A U.S. National Arboretum introduction, it was selected in 1975 from a batch of 1965 seedlings in Delaware, Ohio, and released without patent restrictions in 1990. 'Prospector' proved moderately successful in the US National Elm Trial, averaging a survival rate of 76% overall.
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 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 'dwarf' elm cultivar Ulmus 'Jacqueline Hillier' ('JH') is an elm of uncertain origin. It was cloned from a specimen found in a private garden in Selly Park, Birmingham, England, in 1966. The garden's owner told Hillier that it might have been introduced from outside the country by a relative. Hillier at first conjectured U. minor, as did Heybroek (2009). Identical-looking elm cultivars in Russia are labelled forms of Siberian Elm, Ulmus pumila, which is known to produce 'JH'-type long shoots. Melville considered 'JH' a hybrid cultivar from the 'Elegantissima' group of Ulmus × hollandica. Uncertainty about its parentage has led most nurserymen to list the tree simply as Ulmus 'Jacqueline Hillier'. 'JH' is not known to produce flowers and samarae, or root suckers.
The Siberian elm cultivar Ulmus pumila 'Dwarf Weeper' was discovered in a western Illinois garden and sold by the Arborvillage Nursery Holt, Missouri.
The Siberian elm cultivar Ulmus pumila 'Pinnato-ramosa' was raised by Georg Dieck, as Ulmus pinnato-ramosa, at the National Arboretum, Zöschen, Germany, from seed collected for him circa 1890 in the Ili valley, Turkestan by the lawyer and amateur naturalist Vladislav E. Niedzwiecki while in exile there. Litvinov (1908) treated it as a variety of Siberian elm, U. pumilavar.arborea but this taxon was ultimately rejected by Green, who sank the tree as a cultivar: "in modern terms, it does not warrant recognition at this rank but is a variant of U. pumila maintained and known only in cultivation, and therefore best treated as a cultivar". Herbarium specimens confirm that trees in cultivation in the 20th century as U. pumilaL. var. arboreaLitv. were no different from 'Pinnato-ramosa'.
Ulmus parvifolia, commonly known as the Chinese elm or lacebark elm, is a species native to eastern Asia, including mainland China, Taiwan, Japan, North Korea, South Korea and Vietnam. It has been described as "one of the most splendid elms, having the poise of a graceful Nothofagus".
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 elm cultivar Ulmus 'Turkestanica' was first described by Regel as U. turkestanica in Dieck, Hauptcat. Baumschul. Zöschen (1883) and in Gartenflora (1884). Regel himself stressed that "U. turkestanica was only a preliminary name given by me; I regard this as a form of U. suberosa" [:U. minor ]. Litvinov considered U. turkestanicaRegel a variety of his U. densa, adding that its fruits were "like those of U. foliaceaGilibert" [:U. minor].
Ulmus × intermediaElowsky is a natural hybrid elm occurring across Nebraska and several other Midwestern states, derived from the crossing of Ulmus rubra and Ulmus pumila. As Red Elm U. rubra is far less fertile, and highly susceptible to Dutch elm disease (:DED), it could eventually be hybridized out of existence by U. × intermedia. The hybrid was first reported from the wild in the Chicago region in 1950 and was provisionally named U. × nothaWilhelm & Ware in 1994.
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