112-452: Ulmus americana , generally known as the American elm or, less commonly, as the white elm or water elm , is a species of elm native to eastern North America . The trees can live for several hundred years. It is a very hardy species that can withstand low winter temperatures, but it is affected by Dutch elm disease . The wood was seldom utilized until the advent of mechanical sawing. It
224-407: A microfungus dispersed by bark beetles . In response, disease-resistant cultivars have been developed, capable of restoring the elm to forestry and landscaping . The genus is hermaphroditic , having apetalous perfect flowers which are wind-pollinated. Elm leaves are alternate, with simple, single- or, most commonly, doubly serrate margins, usually asymmetric at the base and acuminate at
336-563: A tetraploid , i.e. having double the usual number of chromosomes, making it unique within the genus. However, a study published in 2011 by the Agricultural Research Service of the United States Department of Agriculture revealed that about 20% of wild American elms are diploid and may even constitute another species. Moreover, several triploid trees known only in cultivation, such as 'Jefferson' , are possessed of
448-661: A few days. They are planted in sandy potting soil at a depth of 1 cm, and germinate in three weeks. Slow-germinating American elm will remain dormant until the second season. Seeds from autumn-flowering elms ripen in the fall and germinate in the spring. Since elms may hybridize within and between species, seed propagation entails a hybridisation risk. In unfavourable seasons, elm seeds are usually sterile. Elms outside their natural range, such as English elm U. minor 'Atinia' , and elms unable to pollinate because pollen sources are genetically identical, are sterile and are propagated by vegetative reproduction . Vegetative reproduction
560-426: A handful of cultivars, causing extremely low genetic diversity. These trees' rapid growth and longevity, leading to great size within decades, made them popular before the advent of DED. Ohio botanist William B. Werthner, discussing the contrast between open-grown and forest-grown American elms, noted that: "In the open, with an abundance of air and light, the main trunk divides into several leading branches which leave
672-519: A height of 34 m (111 ft) and an average crown spread of 24 m (79 ft). The current Tree Register of the British Isles (TROBI) champion grows in Avondale Forest near Rathdrum , County Wicklow , Ireland. The tree had a height of 22.5 m (74 ft) and a dbh of 98 cm (39 in) (circumference of 308 cm or 121 in) when measured in 2000. The tree replaced on
784-423: A high degree of resistance to DED, which ravaged American elms in the 20th century. This suggests that the diploid parent trees, which have markedly smaller cells than the tetraploid, may too be highly resistant to the disease. Ulmus americana was first described and named by Carl Linnaeus in his Species Plantarum , published in 1753. No subspecies or varieties are currently recognized. The American elm
896-486: A leafy canopy over the pavement. However, elms can assume many different sizes and forms depending on the location and climate zone. In 1926 the Klehm Nurseries of Arlington Heights, Illinois , wrote: "American Elms grown in the regular way from seedlings show extreme variability, growing up into trees of all shapes, some of them being very slow in growth while others are moderately rapid in development. The shapes run all
1008-565: A momentary lapse from vacuity. On 21 March 1941 the American elm was made the state tree of Massachusetts . The designation was in commemoration of the fact that George Washington reputedly took command of the Continental Army under an elm. A number of mostly small to medium-sized American elms now survive in woodlands, suburban areas, and occasionally cities, where the survivors have often been relatively isolated from other elms and thus spared
1120-498: A painting by Benjamin West . West made the tree, already a local landmark, famous by incorporating it into his painting after hearing legends (of unknown veracity) about the tree being the location of the treaty. No documentary evidence exists of any treaty Penn signed beneath a particular tree. On March 6, 1810 a great storm blew the tree down. Measurements taken at the time showed it to have a circumference of 24 feet (7.3 m), and its age
1232-468: A result, the population of American elms planted on the Mall and its surrounding areas has remained intact for more than 80 years. Elm wood is valued for its interlocking grain, and consequent resistance to splitting, with significant uses in wagon -wheel hubs, chair seats, and coffins . The bodies of Japanese Taiko drums are often cut from the wood of old elm trees, as the wood's resistance to splitting
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#17328456367191344-637: A severe exposure to the fungus. For example, in Central Park and Tompkins Square Park in New York City , stands of several large elms originally planted by Frederick Law Olmsted survive because of their isolation from neighboring areas in New York where there had been heavy mortality. The Olmsted-designed park system in Buffalo, New York , did not fare as well. A row of mature American elms lines Central Park along
1456-523: A single variety that possessed of any significant resistance. The first, less aggressive strain of the disease fungus, Ophiostoma ulmi , arrived in Europe from Asia in 1910, and was accidentally introduced to North America in 1928. It was steadily weakened by viruses in Europe and had all but disappeared by the 1940s. However, the disease had a much greater and longer-lasting impact in North America, owing to
1568-438: A tying and binding material, even for rope swings for children, and also for making whips . Mary Eleanor Wilkins Freeman , in her 1903 book of short stories, Six Trees , wrote of the American elm: There was not in the whole countryside another tree which could compare with him. He was matchless. Never a stranger passed the elm but stopped, and stared, and said or thought something about it. Even dull rustics looked, and had
1680-440: A velvety texture. The leaves are opposite , pinnately compound , with 7–13 (most often 9) leaflets; each leaf is 20–45 cm (8–18 in) long, the leaflets 7–16 cm ( 2 + 3 ⁄ 4 – 6 + 1 ⁄ 4 in) long and 2.5–5 cm (1–2 in) broad, with a finely toothed margin. The leaflets are sessile , directly attached to the rachis without a petiolule . The flowers are produced in spring shortly before
1792-599: Is a nationwide trial to assess strengths and weaknesses of the 19 leading cultivars raised in the US over a 10-year period; European cultivars have been excluded. Meanwhile, in Europe, American and European cultivars are being assessed in field trials started in 2000 by the UK charity Butterfly Conservation . The oldest American elm trees in New York City's Central Park were planted in the 1860s by Frederick Law Olmsted , making them among
1904-530: Is also a popular wood for making electric guitars and basses, due to its good resonant qualities. Black ash is unique among all trees in North America in that it does not have fibers connecting the growth rings to each other. This is a useful property for basket makers. By pounding on the wood with a mallet, the weaker spring wood layer is crushed, allowing the tougher and darker summer wood layer to be peeled off in long strips. The long strips are trimmed, cleaned, and used in basket weaving . Indigenous peoples of
2016-453: Is also resistant to decay when permanently wet, and hollowed trunks were widely used as water pipes during the medieval period in Europe. Elm was also used as piers in the construction of the original London Bridge , but this resistance to decay in water does not extend to ground contact. The Romans, and more recently the Italians, planted elms in vineyards as supports for vines. Lopped at 3 m,
2128-480: Is also used to produce genetically identical elms (clones). Methods include the winter transplanting of root suckers ; taking hardwood cuttings from vigorous one-year-old shoots in late winter, taking root cuttings in early spring; taking softwood cuttings in early summer; grafting ; ground and air layering ; and micropropagation . A bottom heat of 18 °C and humid conditions are maintained for hard- and softwood cuttings. The transplanting of root suckers remains
2240-518: Is as vectors of DED. American elm is also moderately preferred for feeding and reproduction by the adult elm leaf beetle Xanthogaleruca luteola and highly preferred for feeding by the Japanese beetle Popillia japonica in the United States. U. americana is also the most susceptible of all the elms to verticillium wilt , whose external symptoms closely mimic those of DED. However, the condition
2352-569: Is being paid to trees as sources of energy. In Italy, the Istituto per la Protezione delle Piante is (2012) in the process of releasing to commerce very fast-growing elm cultivars, able to increase in height by more than 2 m (6 ft) per year. Elm bark , cut into strips and boiled, sustained much of the rural population of Norway during the great famine of 1812. The seeds are particularly nutritious, containing 45% crude protein, and less than 7% fibre by dry mass. Elm has been listed as one of
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#17328456367192464-401: Is caused by phytoplasmas that infect the phloem (inner bark) of the tree. Infection and death of the phloem effectively girdles the tree and stops the flow of water and nutrients. The disease affects both wild-growing and cultivated trees. Occasionally, cutting the infected tree before the disease completely establishes itself and cleanup and prompt disposal of infected matter has resulted in
2576-738: Is circa 45, at least 18 of which have probably been lost to cultivation as a consequence of DED or other factors: and others. The disease-resistant selections made available to commerce to date include 'Valley Forge' , 'New Harmony' , 'Princeton' , 'Jefferson' , 'Lewis & Clark' , 'Miller Park' , 'St. Croix' , 'Endurance' , and a set of six different clones collectively known as 'American Liberty' . The United States National Arboretum released 'Valley Forge' and 'New Harmony' in late 1995, after screening tests performed in 1992–1993 showed both had unusually high levels of resistance to DED. 'Valley Forge' performed especially well in these tests. 'Princeton' has been in occasional cultivation since
2688-431: Is far less serious, and afflicted trees should recover the following year. Dutch elm disease (DED) is a fungal disease that has ravaged the American elm, causing catastrophic die-offs in cities across the range. It has been estimated that only approximately 1 in 100,000 American elm trees is DED-tolerant, most known survivors simply having escaped exposure to the disease. However, in some areas still not infested by DED,
2800-479: Is highly desired for nailing the skins to them, and a set of three or more is often cut from the same tree. The elm's wood bends well and distorts easily. The often long, straight trunks were favoured as a source of timber for keels in ship construction. Elm is also prized by bowyers ; of the ancient bows found in Europe, a large portion are elm. During the Middle Ages , elm was also used to make longbows if yew
2912-563: Is highly tolerant of most stress factors. Elms have been able to survive and to reproduce in areas where the disease had eliminated old trees, although most of these young elms eventually succumb to the disease at a relatively young age. There is some reason to hope that these elms will preserve the genetic diversity of the original population, and that they eventually will hybridize with DED-resistant varieties that have been developed or that occur naturally. After 20 years of research, American scientists first developed DED-resistant strains of elms in
3024-546: Is invariably carried by the female parent. Some of these cultivars, notably those with the Siberian elm ( Ulmus pumila ) in their ancestry, lack the forms for which the iconic American elm and English elm were prized. Moreover, several exported to northwestern Europe have proven unsuited to the maritime climate conditions there, notably because of their intolerance of anoxic conditions resulting from ponding on poorly drained soils in winter. Dutch hybridizations invariably included
3136-551: Is much less likely to occur in the wild. American elms have been planted in North America beyond its natural range as far north as central Alberta . It also survives low desert heat at Phoenix, Arizona . Introductions across the Atlantic rarely prospered, even before the outbreak of DED. Introduced to the UK by James Gordon [1] in 1752, the American elm was noted to be far more susceptible to insect foliage damage than native elms. The tree
3248-504: Is native to eastern North America , occurring from Nova Scotia west to Alberta and Montana , and south to Florida and central Texas . It is an extremely hardy tree that can withstand winter temperatures as low as −40 °C (−40 °F). The species occurs naturally in an assortment of habitats, most notably rich bottomlands, floodplains, stream banks, and swampy ground, although it also often thrives on hillsides, uplands and other well-drained soils. On more elevated terrain, as in
3360-491: Is no longer monitored. Sapsucker woodpeckers have a great love of young elm trees. One of the earliest of ornamental elms was the ball-headed graft narvan elm, Ulmus minor 'Umbraculifera' , cultivated from time immemorial in Persia as a shade tree and widely planted in cities through much of south-west and central Asia. From the 18th century to the early 20th century, elms, whether species, hybrids, or cultivars , were among
3472-547: Is not favoured by the vector bark beetles. Thus it becomes colonized and infected only when no other elms are available, a rare situation in western Europe. Research in Spain has suggested that it may be the presence of a triterpene , alnulin , which makes the tree bark unattractive to the beetle species that spread the disease. This possibility, though, has not been conclusively proven. More recently, field elms Ulmus minor highly resistant to DED have been discovered in Spain, and form
Ulmus americana - Misplaced Pages Continue
3584-465: Is the state tree of Massachusetts and North Dakota. The American elm is a deciduous tree which, under ideal conditions, can grow to heights of 21 to 35 meters (69 to 115 feet). The trunk may have a diameter at breast height (dbh) of more than 1.2 m (4 ft), supporting a high, spreading umbrella-like canopy. The leaves are alternate, 7–20 centimeters (3–8 inches) long, with double-serrate margins and an oblique base. The leaves turn yellow in
3696-505: Is thought to have originated in Asia. The two subspecies have now hybridized in Europe where their ranges have overlapped. The hypothesis that O. novo-ulmi arose from a hybrid of the original O. ulmi and another strain endemic to the Himalayas , Ophiostoma himal-ulmi , is now discredited. No sign indicates the current pandemic is waning, and no evidence has been found of a susceptibility of
3808-523: The American elm in excess of 30 m (100 ft), often with a forked trunk creating a vase profile. There are about 30 to 40 species of Ulmus (elm); the ambiguity in number results from difficulty in delineating species, owing to the ease of hybridization between them and the development of local seed-sterile vegetatively propagated microspecies in some areas, mainly in the Ulmus field elm ( Ulmus minor ) group. Oliver Rackham describes Ulmus as
3920-482: The Appalachian Mountains , it is most often found along rivers. The species' wind-dispersed seeds enable it to spread rapidly as suitable areas of habitat become available. American elm fruits in late spring (which can be as early as February and as late as June depending on the climate), the seeds usually germinating immediately, with no cold stratification needed (occasionally some might remain dormant until
4032-459: The Arnold Arboretum using ten other American, European and Asiatic species also ended in failure, attributed to the differences in ploidy and operational dichogamy , although the ploidy factor has been discounted by other authorities. Success was eventually achieved with the autumn-flowering Chinese elm Ulmus parvifolia by the late Prof. Eugene Smalley towards the end of his career at
4144-580: The Iliad , when the River Scamander , indignant at the sight of so many corpses in his water, overflows and threatens to drown Achilles, the latter grasps a branch of a great elm in an attempt to save himself ("ὁ δὲ πτελέην ἕλε χερσὶν εὐφυέα μεγάλην". The nymphs also planted elms on the tomb in the Thracian Chersonese of "great-hearted Protesilaus " ("μεγάθυμου Πρωτεσιλάου"), the first Greek to fall in
4256-592: The Siberian elm is drought tolerant, in dry countries, new varieties of elm are often root-grafted onto this species. Dutch elm disease (DED) devastated elms throughout Europe and much of North America in the second half of the 20th century. It derives its name "Dutch" from the first description of the disease and its cause in the 1920s by Dutch botanists Bea Schwarz and Christina Johanna Buisman . Owing to its geographical isolation and effective quarantine enforcement, Australia has so far remained unaffected by DED, as have
4368-507: The University of Wisconsin–Madison after he overcame the problem of keeping Chinese elm pollen alive until spring. Only one of the hybrid clones was commercially released, as 'Rebella' in 2011 by the German nursery Eisele GmbH; the clone is not available in the United States. Other artificial hybridizations with American elm are rare, and now regarded with suspicion. Two such alleged successes by
4480-705: The White House in Washington, D.C. The trees, whose maintenance the National Park Service (NPS) manages, remain healthy and are thriving. However, it has been noted that U. americana cultivars are not recommended for more than singular plantings as they have unresolved DED and elm yellows concerns. It has also been noted that monoculture plantings of U. americana cultivars, such as those along Pennsylvania Avenue, have disproportionate vulnerabilities to disease. Further, long-term studies of 'Princeton' in Europe and
4592-458: The apex . The fruit is a round wind-dispersed samara flushed with chlorophyll , facilitating photosynthesis before the leaves emerge. The samarae are very light, those of British elms numbering around 50,000 to the pound (454 g ). (Very rarely anomalous samarae occur with more than two wings. ) All species are tolerant of a wide range of soils and pH levels but, with few exceptions, demand good drainage. The elm tree can grow to great height,
Ulmus americana - Misplaced Pages Continue
4704-413: The black ash , is a species of ash native to much of eastern Canada and the northeastern United States, from western Newfoundland west to southeastern Manitoba , and south to Illinois and northern Virginia . Formerly abundant, as of 2017 the species is threatened with near total extirpation throughout its range within the next century as a result of infestation by an invasive parasitic insect known as
4816-421: The emerald ash borer ( Agrilus planipennis ). Black ash is a medium-sized deciduous tree reaching 15–20 metres (49–66 ft) (exceptionally 26 metres (85 ft)) tall with a trunk up to 60 cm (24 inches) diameter, or exceptionally to 160 cm (63 inches). The bark is grey, thick and corky even on young trees, becoming scaly and fissured with age. The winter buds are dark brown to blackish, with
4928-439: The xylem and are thus relatively ineffective. The American elm's biology in some ways has helped to spare it from obliteration by DED, in contrast to what happened to the American chestnut with the chestnut blight . The elm's seeds are largely wind-dispersed, and the tree grows quickly and begins bearing seeds at a young age. It grows well along roads or railroad tracks, and in abandoned lots and other disturbed areas, where it
5040-498: The 1920s. 'Princeton' gained renewed attention after its performance in the 1992–1993 screening tests showed that it also had a high degree of disease resistance. A later test performed in 2002–2003 confirmed the disease resistance of 'Princeton', 'Valley Forge' and 'New Harmony', as well as that of 'Jefferson'. Thus far, plantings of these four varieties generally appear to be successful. In 2005, approximately 90 'Princeton' elms were planted along Pennsylvania Avenue in front of
5152-467: The 19th century, while in northern Japan Japanese elm ( U. davidiana var. japonica ) was widely planted as a street tree. From about 1850 to 1920, the most prized small ornamental elm in parks and gardens was the 'Camperdown' elm ( U. glabra 'Camperdownii') , a contorted, weeping cultivar of the wych elm grafted on to a nonweeping elm trunk to give a wide, spreading, and weeping fountain shape in large garden spaces. In northern Europe, elms were among
5264-654: The 38 substances that are used to prepare Bach flower remedies , a kind of alternative medicine . Chinese elm ( Ulmus parvifolia ) is a popular choice for bonsai owing to its tolerance of severe pruning. In 1997, a European Union elm project was initiated, its aim to coordinate the conservation of all the elm genetic resources of the member states and, among other things, to assess their resistance to Dutch elm disease. Accordingly, over 300 clones were selected and propagated for testing. Many elm trees of various kinds have attained great size or otherwise become particularly noteworthy. Many artists have admired elms for
5376-622: The American elm ( U. americana ), resulting in the release of DED-resistant clones, notably the cultivars 'Valley Forge' and 'Jefferson' . Much work has also been done into the selection of disease-resistant Asiatic species and cultivars. In 1993, Mariam B. Sticklen and James L. Sherald reported the results of experiments funded by the US National Park Service and conducted at Michigan State University in East Lansing that were designed to apply genetic engineering techniques to
5488-676: The American elm continues to thrive, notably in Florida , Alberta and British Columbia . There is a notable grove of old American elm trees in Manhattan 's Central Park . The trees there were apparently spared because of the grove's isolation in such an intensely urban setting. The American elm is particularly susceptible to disease because the period of infection often coincides with the period, approximately 30 days, of rapid terminal growth when new springwood vessels are fully functional. Spores introduced outside of this period remain largely static within
5600-620: The Avenue of Honour in Bacchus Marsh , Victoria. In addition, a heritage-listed planting of American elms can be found along Grant Crescent in Griffith, Australian Capital Territory . American elms are only rarely found in New Zealand. Numerous cultivars have been raised, originally for their aesthetic merit but more recently for their resistance to Dutch elm disease The total number of named cultivars
5712-680: The Columbian Silkmoth ( Hyalophora columbia ) and the Banded Tussock Moth (Pale Tiger Moth) ( Halysidota tessellaris ). The American elm is susceptible to Dutch Elm Disease and to elm yellows . In North America, there are three species of elm bark beetles: one native, Hylurgopinus rufipes ("native elm bark beetle"); and two invasive, Scolytus multistriatus ("smaller European elm bark beetle") and Scolytus schevyrewi ("banded elm bark beetle"). Although intensive feeding by elm bark beetles can kill weakened trees, their main impact
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#17328456367195824-569: The Himalayan elm ( Ulmus wallichiana ) as a source of antifungal genes and have proven more tolerant of wet ground; they should also ultimately reach a greater size. However, the susceptibility of the cultivar 'Lobel', used as a control in Italian trials, to elm yellows has now (2014) raised a question mark over all the Dutch clones. Several highly resistant Ulmus cultivars have been released since 2000 by
5936-645: The Institute of Plant Protection in Florence, most commonly featuring crosses of the Dutch cultivar 'Plantijn' with the Siberian elm to produce resistant trees better adapted to the Mediterranean climate. Elms take many decades to grow to maturity, and as the introduction of these disease-resistant cultivars is relatively recent, their long-term performance and ultimate size and form cannot be predicted with certainty. The National Elm Trial in North America, begun in 2005,
6048-681: The List of elm species is largely based on that established by Brummitt. A large number of synonyms have accumulated over the last three centuries; their currently accepted names can be found in the list of Elm synonyms and accepted names . Botanists who study elms and argue over elm identification and classification are called "pteleologists", from the Greek πτελέα (elm). As part of the suborder urticalean rosids , they are distantly related to cannabis , mulberries , figs , hops , and nettles . Elm propagation methods vary according to elm type and location, and
6160-829: The Middle East to Lebanon and Israel, and across the Equator in the Far East into Indonesia. Elms are components of many kinds of natural forests . Moreover, during the 19th and early 20th centuries, many species and cultivars were also planted as ornamental street, garden, and park trees in Europe , North America, and parts of the Southern Hemisphere , notably Australasia . Some individual elms reached great size and age. However, in recent decades, most mature elms of European or North American origin have died from Dutch elm disease , caused by
6272-476: The Netherlands in 1928 and continued, uninterrupted by World War II, until 1992. Similar programmes were initiated in North America (1937), Italy (1978) and Spain (1986). Research has followed two paths: In North America, careful selection has produced a number of trees resistant not only to DED, but also to the droughts and cold winters that occur on the continent. Research in the United States has concentrated on
6384-492: The Northeastern Woodlands also make bark baskets from black ash, traditionally used for berry-gathering. North American native ash tree species are used by North American frogs as a critical food source, as the leaves that fall from the trees are particularly suitable for tadpoles to feed upon in ponds (both temporary and permanent), large puddles, and other water sources. Species such as red maple, which are taking
6496-550: The Trojan War. These elms grew to be the tallest in the known world, but when their topmost branches saw far off the ruins of Troy, they immediately withered, so great still was the bitterness of the hero buried below, who had been loved by Laodamia and slain by Hector . The story is the subject of a poem by Antiphilus of Byzantium (first century AD) in the Palatine Anthology : Fraxinus nigra Fraxinus nigra ,
6608-425: The United States have suggested that the cultivar's resistance to DED may be limited (see Pests and diseases of 'Princeton' ). The National Elm Trial evaluated 19 elm cultivars commercially available in the United States in scientific plantings throughout the nation to assess and compare the strengths and weaknesses of each. The trial, which started in 2005, lasted for ten years. Based on the trial's final ratings,
6720-508: The absence of the predators in their native lands. In Australia, introduced elm trees are sometimes used as food plants by the larvae of hepialid moths of the genus Aenetus . These burrow horizontally into the trunk then vertically down. Circa 2000, the Asian Zig-zag sawfly Aproceros leucopoda appeared in Europe and North America, although in England, its impact has been minimal and it
6832-664: The age of three, the infant goddess Artemis practised her newly acquired silver bow and arrows, made for her by Hephaestus and the Cyclopes , by shooting first at an elm, then at an oak, before turning her aim on a wild animal: The first reference in literature to elms occurs in the Iliad . When Eetion , father of Andromache , is killed by Achilles during the Trojan War , the mountain nymphs plant elms on his tomb ("περί δὲ πτελέας ἐφύτευσαν νύμφαι ὀρεστιάδες, κoῦραι Διὸς αἰγιόχoιo"). Also in
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#17328456367196944-451: The basis of a major breeding programme. Owing to their innate resistance to DED, Asiatic species have been crossed with European species, or with other Asiatic elms, to produce trees that are both highly resistant to disease and tolerant of native climates. After a number of false dawns in the 1970s, this approach has produced a range of reliable hybrid cultivars now commercially available in North America and Europe. Disease resistance
7056-479: The beetles, invade the xylem or vascular system. The tree responds by producing tyloses , effectively blocking the flow from roots to leaves. Woodland trees in North America are not quite as susceptible to the disease because they usually lack the root grafting of the urban elms and are somewhat more isolated from each other. In France, inoculation with the fungus of over 300 clones of the European species failed to find
7168-461: The black ash, or wisqoq, has been vital to the Mi'kmaw culture and was used to make many functional items like chairs, canoes, axes, snowshoes, and most notably, baskets. The sale of black ash baskets sustained many Mi'kmaw families when income was scarce. The Shakers also made extensive use of the black ash for creating baskets. Also called basket ash, brown ash, swamp Ash, hoop ash, and water ash. It
7280-506: The campus in recent years. The largest surviving urban forest of American elms in North America is believed to be in the city of Winnipeg, Manitoba , Canada, where close to 200,000 elms remain. The city of Winnipeg spends $ 3 million annually to aggressively combat the disease utilizing Dursban Turf and the Dutch Trig vaccine, losing 1,500–4,000 trees per year. Governmental agencies, educational institutions or other organizations in most of
7392-515: The closely related green ash . Its fall foliage is yellow. Black ash is one of the first trees to lose its leaves in the fall. It is very closely related to Manchurian ash , and will easily hybridize with it. Some consider the two to be geographic isolates of each other. The species was considered abundant and its survival of little concern prior to the invasion of the emerald ash borer , first detected in North America in 2002. However, since that time this invasive insect has spread throughout most of
7504-642: The countryside, the former in northern areas including Scandinavia and northern Britain , the latter further south. The hybrid between these two, Dutch elm ( U. × hollandica ) , occurs naturally and was also commonly planted. In much of England, the English elm later came to dominate the horticultural landscape. Most commonly planted in hedgerows, it sometimes occurred in densities over 1000/km . In south-eastern Australia and New Zealand, large numbers of English and Dutch elms, as well as other species and cultivars, were planted as ornamentals following their introduction in
7616-566: The development of DED-resistant strains of American elm trees. In 2007, A. E. Newhouse and F. Schrodt of the State University of New York College of Environmental Science and Forestry in Syracuse reported that young transgenic American elm trees had shown reduced DED symptoms and normal mycorrhizal colonization. In Europe, the European white elm ( U. laevis ) has received much attention. While this elm has little innate resistance to DED, it
7728-424: The development of DED-resistant strains of American elm trees. In 2007, AE Newhouse and F Schrodt of the State University of New York College of Environmental Science and Forestry in Syracuse reported that young transgenic American elm trees had shown reduced DED symptoms and normal mycorrhizal colonization. Thousands of attempts to cross the American elm with the Siberian elm U. pumila failed. Attempts at
7840-484: The disease is evident. In the 19th and early 20th century, American elm was a common street and park tree owing to its tolerance of urban conditions, rapid growth, and graceful form. This however led to extreme overplanting of the species, especially to form living archways over streets, which ultimately produced an unhealthy monoculture of elms that had no resistance to disease and pests. Elms do not naturally form pure stands and trees used in landscaping were grown from
7952-511: The ease and grace of their branching and foliage, and have painted them with sensitivity. Elms are a recurring element in the landscapes and studies of, for example, John Constable , Ferdinand Georg Waldmüller , Frederick Childe Hassam , Karel Klinkenberg , and George Inness . In Greek mythology, the nymph Ptelea (Πτελέα, Elm) was one of the eight hamadryads , nymphs of the forest and daughters of Oxylos and Hamadryas. In his Hymn to Artemis , poet Callimachus (third century BC) tells how, at
8064-422: The easiest most and common propagation method for European field elm and its hybrids. For specimen urban elms, grafting to wych-elm rootstock may be used to eliminate suckering or to ensure stronger root growth. The mutant-elm cultivars are usually grafted, the "weeping" elms 'Camperdown' and 'Horizontalis' at 2–3 m (7–10 ft), the dwarf cultivars 'Nana' and 'Jacqueline Hillier' at ground level. Since
8176-451: The elms' quick growth, twiggy lateral branches, light shade, and root suckering made them ideal trees for this purpose. The lopped branches were used for fodder and firewood. Ovid in his Amores characterizes the elm as "loving the vine": ulmus amat vitem, vitis non deserit ulmum (the elm loves the vine, the vine does not desert the elm), and the ancients spoke of the "marriage" between elm and vine . The mucilaginous inner bark of
8288-586: The entire length of Fifth Avenue from 59th to 110th Streets. In Akron, Ohio , there is a very old elm tree that has not been infected. In historical areas of Philadelphia, Pennsylvania , there are also a few mature American elms still standing — notably in Independence Square and the Quadrangle at the University of Pennsylvania , and also at the nearby campuses of Haverford College , Swarthmore College , and Pennsylvania State University , believed to be
8400-411: The fall. The perfect flowers are small, purple-brown and, being wind-pollinated, apetalous . The flowers are also protogynous , the female parts maturing before the male, thus reducing, but not eliminating, self-fertilization, and emerge in early spring before the leaves. The fruit is a flat samara 2 cm ( 3 ⁄ 4 in) long by 1.5 cm broad, with a circular papery wing surrounding
8512-566: The few trees tolerant of saline deposits from sea spray, which can cause "salt-burning" and die-back. This tolerance made elms reliable both as shelterbelt trees exposed to sea wind, in particular along the coastlines of southern and western Britain and in the Low Countries, and as trees for coastal towns and cities. This belle époque lasted until the First World War , when the elm began its slide into horticultural decline. The impact of
8624-648: The first two of these types also occurring in Canada. A sugar maple - ironwood -American elm cover type occurs on some hilltops near Témiscaming , Quebec . The leaves of the American elm serve as food for the larvae of a number of species of Lepidoptera . These include such butterflies as the Eastern Comma ( Polygonia comma ), Question Mark ( Polygonia interrogationis ), Mourning Cloak ( Nymphalis antiopa ), Painted Lady ( Vanessa cardui ) and Red-spotted Purple ( Limenitis arthemis astyanax ), as well as such moths as
8736-676: The following year). The species attains its greatest growth potential in the Northeastern US, while elms in the Deep South and Texas grow much smaller and have shorter lifespans, although conversely their survival rate in the latter regions is higher owing to the climate being less favorable to the spread of DED. In the United States, the American elm is a principal member of four major forest cover types: black ash -American elm- red maple ; silver maple -American elm; sugarberry -American elm- green ash ; and sycamore - sweetgum -American elm, with
8848-489: The fungus to a disease of its own caused by d-factors : naturally occurring virus-like agents that severely debilitated the original O. ulmi and reduced its sporulation. Elm phloem necrosis (elm yellows) is a disease of elm trees that is spread by leafhoppers or by root grafts. This very aggressive disease, with no known cure, occurs in the Eastern United States , southern Ontario in Canada, and Europe. It
8960-510: The greater susceptibility of the American elm, Ulmus americana , which masked the emergence of the second, far more virulent strain of the disease Ophiostoma novo-ulmi . It appeared in the United States sometime in the 1940s, and was originally believed to be a mutation of O. ulmi . Limited gene flow from O. ulmi to O. novo-ulmi was probably responsible for the creation of the North American subspecies O. novo-ulmi subsp. americana . It
9072-510: The hostilities on Germany , the origin of at least 40 cultivars, coincided with an outbreak of the early strain of DED, Ophiostoma ulmi . The devastation caused by the Second World War , and the demise in 1944 of the huge Späth nursery in Berlin , only accelerated the process. The outbreak of the new, three times more virulent, strain of DED Ophiostoma novo-ulmi in the late 1960s, brought
9184-686: The largest remaining stand in the country. There are several large American Elm trees in western Massachusetts. A large specimen, which stands on Summer Street in the Berkshire County town of Lanesborough, Massachusetts , has been kept alive by antifungal treatments. Rutgers University has preserved 55 mature elms on and in the vicinity of Voorhees Mall on the College Avenue Campus in New Brunswick, New Jersey in addition to seven disease-resistant trees that have been planted in this area of
9296-506: The late 1990s. Elms in forest and other natural areas have been less affected by DED than trees in urban environments due to lower environmental stress from pollution and soil compaction and due to occurring in smaller, more isolated populations. Fungicidal injections can be administered to valuable American elms, to prevent infection. Such injections generally are effective as a preventive measure for up to three years when performed before any symptoms have appeared, but may be ineffective once
9408-660: The majority of the trees, although several are still lost each year. Younger American elms that have been planted in Central Park since the outbreak are of the DED-resistant 'Princeton' and 'Valley Forge' cultivars. Several rows of American elm trees that the National Park Service (NPS) first planted during the 1930s line much of the 1.9-mile-length (3 km) of the National Mall in Washington, DC. DED first appeared on
9520-513: The most critical genus in the entire British flora, adding that 'species and varieties are a distinction in the human mind rather than a measured degree of genetic variation'. Eight species are endemic to North America and three to Europe, but the greatest diversity is in Asia with approximately two dozen species. The oldest fossils of Ulmus are leaves dating Paleocene , found across the Northern Hemisphere. The classification adopted in
9632-408: The most widely planted ornamental trees in both Europe and North America. They were particularly popular as a street tree in avenue plantings in towns and cities, creating high-tunnelled effects. Their quick growth and variety of foliage and forms, their tolerance of air-pollution, and the comparatively rapid decomposition of their leaf litter in the fall were further advantages. In North America,
9744-467: The new leaves, in loose panicles ; they are inconspicuous with no petals, and are wind-pollinated. The fruit is a samara 2.5–4.5 cm (1– 1 + 3 ⁄ 4 in) long comprising a single seed 2 cm ( 3 ⁄ 4 in) long with an elongated apical wing 1.5–2 cm ( 5 ⁄ 8 – 3 ⁄ 4 in) long and 6–8 mm ( 1 ⁄ 4 – 5 ⁄ 16 in) broad. Black ash commonly occurs in swamps , often with
9856-474: The nursery trade were 'Hamburg' , and 'Kansas Hybrid' , both with Siberian elm Ulmus pumila . However, given the repeated failure with the two species by research institutions, it is now believed that the "American elm" in question was more likely to have been the red elm, Ulmus rubra . The American elm's wood is coarse, hard, and tough, with interlacing, contorted fibers that make it difficult to split or chop, and cause it to warp after sawing. Accordingly,
9968-641: The oldest stands of American elms in the world. Along the Mall and Literary Walk four lines of American elms stretch over the walkway forming a cathedral-like covering. A part of New York City's urban ecology , the elms improve air and water quality, reduce erosion and flooding, and decrease air temperatures during warm days. While the stand is still vulnerable to DED, in the 1980s the Central Park Conservancy undertook aggressive countermeasures such as heavy pruning and removal of extensively diseased trees. These efforts have largely been successful in saving
10080-503: The pandemic, and a number may survive, or have regenerated, unrecognised. Enthusiasm for the newer clones often remains low owing to the poor performance of earlier, supposedly disease-resistant Dutch trees released in the 1960s and 1970s. In the Netherlands, sales of elm cultivars slumped from over 56,000 in 1989 to just 6,800 in 2004, whilst in the UK , only four of the new American and European releases were commercially available in 2008. Efforts to develop DED-resistant cultivars began in
10192-476: The place of ash, due to the ash borer, are much less suitable for the frogs as a food source—resulting in poor frog survival rates and small frog sizes. It is the lack of tannins in the American ash variety that makes them good for the frogs as a food source and also not resistant to the ash borer. Varieties of ash from outside North America typically have much higher tannin levels and resist the borer. Maples and various non-native invasive trees, trees that are taking
10304-475: The plant's survival via stump sprouts. Most serious of the elm pests is the elm leaf beetle Xanthogaleruca luteola , which can decimate foliage, although rarely with fatal results. The beetle was accidentally introduced to North America from Europe. Another unwelcome immigrant to North America is the Japanese beetle Popillia japonica . In both instances, the beetles cause far more damage in North America owing to
10416-434: The plantsman's needs. Native species may be propagated by seed. In their natural setting, native species, such as wych elm and European white elm in central and northern Europe and field elm in southern Europe, set viable seed in "favourable" seasons. Optimal conditions occur after a late warm spring. After pollination, seeds of spring-flowering elms ripen and fall at the start of summer (June); they remain viable for only
10528-536: The preferred cultivars of U. americana are 'New Harmony' and 'Princeton'. 'Jefferson' was released to wholesale nurseries in 2004 and is becoming increasingly available for planting. However, 'Jefferson' has not been widely tested beyond Washington, D.C. The National Elm Trial provided no data on ‘Jefferson’ because an error in tree identification had occurred earlier in the nursery trade. The error may still be causing nurseries to sell 'Princeton' elms that are mislabeled as 'Jefferson', although one can distinguish between
10640-402: The provinces of Alberta and British Columbia in western Canada . DED is caused by a micro fungus transmitted by two species of Scolytus elm-bark beetles , which act as vectors . The disease affects all species of elms native to North America and Europe, but many Asiatic species have evolved antifungal genes and are resistant. Fungal spores, introduced into wounds in the tree caused by
10752-726: The register a larger champion located in Woodvale Cemetery in Sussex , England, which in 1988 had a height of 27 metres (89 ft) and a diameter of 115 cm (45 in) or circumference of 361 cm (142 in). A prime example of the species was the Sauble Elm, which grew beside the banks of the Sauble River in Ontario , Canada, to a height of 43 m (140 ft), with a dbh of 196 cm (77 in) before succumbing to DED; when it
10864-436: The single 4.5 millimeters ( 1 ⁄ 8 inch) seed . As in the closely related Ulmus laevis (European white elm), the flowers and seeds are borne on 1–3 cm long stems. American elm is wholly insensitive to daylight length ( photoperiod ), and will continue to grow well into autumn until injured by frost. Ploidy is 2n = 56, or more rarely, 2n = 28. For over 80 years, U. americana had been identified as
10976-587: The slippery elm ( Ulmus rubra ) has long been used as a demulcent , and is still produced commercially for this purpose in the US with approval for sale as a nutritional supplement by the Food and Drug Administration . Elms also have a long history of cultivation for fodder , with the leafy branches cut to feed livestock . The practice continues today in the Himalaya, where it contributes to serious deforestation. As fossil fuel resources diminish, increasing attention
11088-402: The species most commonly planted was the American elm ( U. americana ), which had unique properties that made it ideal for such use - rapid growth, adaptation to a broad range of climates and soils, strong wood, resistance to wind damage, and vase-like growth habit requiring minimal pruning . In Europe, the wych elm ( U. glabra ) and the field elm ( U. minor ) were the most widely planted in
11200-471: The states that are within the United States maintain lists of champion or big trees that describe the locations and characteristics of those states' largest American elm trees (see List of state champion American elm trees ). The current U.S. national champion American elm tree is located in Iberville Parish, Louisiana . When measured in 2010, the tree had a trunk circumference of 820 cm (324 in),
11312-452: The tree to its nadir. Since around 1990, the elm has enjoyed a renaissance through the successful development in North America and Europe of cultivars highly resistant to DED. Consequently, the total number of named cultivars, ancient and modern, now exceeds 300, although many of the older clones, possibly over 120, have been lost to cultivation. Some of the latter, however, were by today's standards inadequately described or illustrated before
11424-406: The tree's range, and within a few years black ash is expected to be all but extirpated; a similar fate awaits green ash. In 2014, a U.S. Forest Service agent estimated that "ninety-nine percent of the ashes in North America are probably going to die." Blue ash and white ash are only slightly less affected. In Mi'kma'ki (made up of Nova Scotia , New Brunswick and eastern Quebec , Canada ),
11536-406: The trees during the 1950s and reached a peak in the 1970s. The NPS used a number of methods to control the epidemic , including sanitation , pruning , injecting trees with fungicide , and replanting with DED-resistant cultivars. The NPS combated the disease's local insect vector , the smaller European elm bark beetle ( Scolytus multistriatus ), by trapping and by spraying with insecticides . As
11648-516: The trunk at a sharp angle and continue to grow upward, gradually diverging, dividing and subdividing into long, flexible branchlets whose ends, at last, float lightly in the air, giving the tree a round, somewhat flattened top of beautifully regular proportions and characteristically fine twiggery." It is this distinctive growth form that is so valued in the open-grown American elms of street plantings, lawns, and parks; along most narrower streets, elms planted on opposite sides arch and blend together into
11760-594: The two cultivars as the trees mature. In 2007, the 'Elm Recovery Project' from the University of Guelph in Ontario, Canada, reported that cuttings from healthy surviving old elms surveyed across Ontario had been grown to produce a bank of resistant trees, isolated for selective breeding of highly resistant cultivars. In 1993, Mariam B. Sticklen and James L. Sherald reported the results of NPS-funded experiments conducted at Michigan State University in East Lansing that were designed to apply genetic engineering techniques to
11872-403: The way from the true open excurrent growth to globular, or flat-topped, or pendant. As regards foliage, the leaves are from small to medium large, some shedding early and others late. This condition makes it difficult for the landscape architect to choose just the right trees to obtain the effect desired." The classic vase-shaped elm was mainly the result of selective breeding of a few cultivars and
11984-441: The wood originally had few uses, save for making hubs for wagon wheels . Later, with the advent of mechanical sawing, American elm wood was used for barrel staves, trunk-slats , and hoop-poles , and subsequently became fundamental to the manufacture of wooden automobile bodies, with the intricate fibers holding screws unusually well. Young twigs and branchlets of the American elm have tough, fibrous bark that has been used as
12096-462: Was estimated to be 280 years. Wood from the tree was made into furniture, canes, walking sticks and various trinkets that Philadelphians kept as relics. Elm See Elms are deciduous and semi-deciduous trees comprising the genus Ulmus in the family Ulmaceae . They are distributed over most of the Northern Hemisphere, inhabiting the temperate and tropical - montane regions of North America and Eurasia, presently ranging southward in
12208-423: Was felled in 1968, a tree-ring count established that it had germinated in 1701. Other large or otherwise significant American elm trees have included: The Treaty Elm, Philadelphia , Pennsylvania . In what is now Penn Treaty Park , the founder of Pennsylvania , William Penn , is said to have entered into a treaty of peace in 1683 with the native Lenape Turtle Clan under a picturesque elm tree immortalized in
12320-521: Was first recognized in Britain in the early 1970s, believed to have been introduced via a cargo of Canadian rock elm destined for the boatbuilding industry, and rapidly eradicated most of the mature elms from western Europe. A second subspecies, O. novo-ulmi subsp. novo-ulmi , caused similar devastation in Eastern Europe and Central This subspecies, which was introduced to North America, and like O. ulmi ,
12432-523: Was propagated and marketed in the UK by the Hillier & Sons nursery, Winchester, Hampshire from 1945, with 450 sold in the period 1962 to 1977 when production ceased with the advent of the more virulent form of Dutch elm disease. Introduced to Australasia , the tree was listed by Australian nurseries in the early 20th century. It is known to have been planted along the Avenue of Honour at Ballarat , Victoria and
12544-589: Was unavailable. The first written references to elm occur in the Linear B lists of military equipment at Knossos in the Mycenaean period . Several of the chariots are of elm (" πτε-ρε-ϝα ", pte-re-wa ), and the lists twice mention wheels of elmwood. Hesiod says that ploughs in Ancient Greece were also made partly of elm. The density of elm wood varies between species, but averages around 560 kg/m . Elm wood
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