Ulmus americana is the state tree for Massachusetts and for North Dakota.
The American elm is susceptible to numerous diseases, including Dutch elm disease. Ulmus americana has been a street and shade tree of choice because of its fast growth and pleasant shape and size. The species still exists in substantial numbers both as shade trees and in nature.
Numerous infraspecific taxa have been recognized in Ulmus americana (A. J. Rehder 1949; P. S. Green 1964).
Native American tribes frequently used parts of Ulmus americana for a variety of medicinal purposes, including treatment of coughs and colds, sore eyes, dysentary, diarrhea, broken bones, gonorrhea, and pulmonary hemorrhage, as a gynecological aid, as a bath for appendicitis, and as a wash for gunwounds (D. E. Moerman 1986).
Wildlife uses include seed eating by granivorous birds, bird cover, bird nesting sites, and substrate for insectivorous birds. Seeds feed small mammals. It is a larval host for Mourning Cloak (Nymphalis antiopa), Columbia silkmoth (Hyalophora columbia), Question Mark (Polygonia interrogationis), Painted Lady (Vanessa cardui), and Eastern Comma (Polygonia comma). (NPIN, 2008)
USA: AL , AR , CT , DE , FL , GA , IL , IN , IA , KS , KY , LA , ME , MD , MA , MI , MN , MS , MO , MT , NE , NH , NJ , NY , NC , ND , OH , OK , PA , RI , SC , SD , TN , TX , VT , VA , WV , WI , WY , DC (NPIN, 2008)
Canada: MB , NB , NS , ON , PE , QC , SK (NPIN, 2008)
Native Distribution: N.S., s. Man & s.e. Sask. & Crook Co. WY, s. to FL & c. TX (NPIN, 2008)
USDA Native Status: L48(N), CAN(N) (NPIN, 2008)
Flowers are green. (USDA PLANTS, 2009) Flowers are borne in axils on the old twigs. Calyx is bell-shaped and 4-9-lobed. Flowers hang on long drooping pedicels. (Peattie, 1930) Flowers bloom in clusters along the stem. (Hultman, 1978) They have no petals. (Weeks et al, 2005) Bloom color is red or green. (NPIN, 2008) Flowers are born on a shallowly lobed calyx. They are slightly asymmetric, with 7-9 lobes and ciliate margins. There are 7-9 stamens. Anthers are red and stigmas are white-ciliate and deeply divided. (FNA, 2006)
Fruit is brown. (USDA PLANTS, 2009) The samara (winged fruit) is rounded, the wing continuous all around except at the apex. Fruit may be oval or ovate, and is ciliate with fine hairs on the margins. (Peattie, 1930) Single seeds are each surrounded by a papery wing. (Hultman, 1978) Fruit is round and flat with hairy margins. The tip is deeply notched. (Weeks et al, 2005) The fruit is a yellowish to cream samara with narrow wings and hairy edges. Seeds are thick but not inflated. (UW, 2009) Samaras are yellow-cream when mature, though sometimes tinged with reddish purple (particularly in the Southern range of species). They are arrowly winged, with ciliate margins. Cilia are yellow to white. (FNA, 2006)
Leaves are green and coarse. (USDA PLANTS, 2009) Leaves are obovate-oblong and abruptly pointed. Leaves are oval, unequal-sided at the base, and sharply doubly serrate. They are rough above, dull green, and paler below. (Peattie, 1930) Elliptical with a coarsely double-toothed edge, and tapering to a point. (Hultman, 1978) Simple leaves that have a lop-sided base. Fall coloration is yellow. (Weeks et al, 2005) Dark-green leaves have variable fall color. (NPIN, 2008)
Stems This tree has a single stem growth habit. (USDA PLANTS, 2009) Erect arching branches form an umbrella-shaped crown. Twigs and buds are smooth or sparingly pubescent. (Peattie, 1930) Alternate branching is typical. Buds are elongate with chestnut-brown, slightly hairy scales. Twigs zig-zag from node to node. Lateral leaf buds lie against the twig. (Weeks et al, 2005) usually forked into many spreading branches, drooping at ends, forming a very broad, rounded, flat-topped or vaselike crown, often wider than high. (UW, 2009) Old-growth branches are smooth and not winged. Twigs are brown and pubescent to glabrous. (FNA, 2006)
Bark is flaky and gray. (Peattie, 1930) Bark is gray and tough. (Hultman, 1978) Bark is spongy until mature, and is tannish gray with thick, interlacing ridges. Inner bark is two-toned with light and dark layers. It is tan colored and spongy when young. (Weeks et al, 2005)
Tree height at 20 years is a maximum of 50' tall, at maturity 120.0' tall. (USDA PLANTS, 2009) Tree may be 50-100' tall. (Hultman, 1978) The tree was once 100'+ regularly, but is now more commonly 30-40'. (Weeks et al, 2005) It usually grows 60-80'. (NPIN, 2008)
Flowers inflorescence is less than 1" hanging cluster. (UW, 2009) Fascicles are less than 2.5 cm and the pedicel is 1-2 cm. (FNA, 2006)
Fruit is ovate and roughly 1 cm. Cilia to 1 mm. (FNA, 2006)
Leaves 4-6" long. (Hultman, 1978) Petiole is roughly 5 mm. Leaves are 7-14 × 3-7 cm. (FNA, 2006)
Various preparations of bark were used by pregnant women to insure stability of children, for menstrual cramps, for colds, for severe coughs, for dysentery, for "summer disease-vomiting, diarrhea and cramps," to facilitate childbirth and for parturition, for broken bones, for appendicitis, for sore eyes as an eye lotion, for gonorrhea, and for pulmonary hemorrhage. An infusion of root bark was taken for excessive menstruation. Wood was used in various capacities as a structural and vessel building material. (UM, 2009)
Amerika qarağacı (lat. Ulmus americana) — qarağackimilər fəsiləsinin qarağac cinsinə aid bitki növü.
Amerika qarağacı (lat. Ulmus americana) — qarağackimilər fəsiləsinin qarağac cinsinə aid bitki növü.
Die Amerikanische Ulme (Ulmus americana), auch Weiß-Ulme genannt,[1] ist eine Pflanzenart aus der Gattung der Ulmen (Ulmus) innerhalb der Familie der Ulmengewächse (Ulmaceae). Sie ist in Nordamerika weitverbreitet. Sie wird als Zierpflanze und im Landschaftsbau verwendet. Die Bestände der Amerikanischen Ulme wurden aufgrund des Pilzes Ceratocystis ulmi in der zweiten Hälfte des 20. Jahrhunderts stark dezimiert (Ulmensterben).[2]
Die Exemplare der Amerikanischen Ulme können 175 bis 200 alt werden; ein Alter von etwa 300 Jahren wird von wenigen Einzelexemplaren berichtet.[3]
Die Amerikanische Ulme wächst als laubabwerfender, sommergrüner Baum.[4][5] In dichten Waldbeständen werden Wuchshöhen von 30 bis 36 Metern sowie Brusthöhendurchmesser (BHD) von 122 bis 152 Zentimetern erreicht. Auf durchschnittlichen Standorten sind Wuchshöhen von etwa 24 Metern üblich, aber an sehr feuchten oder sehr trockenen Standorten erreichen ausgewachsene Exemplare nur Wuchshöhen von 12 bis 18 Metern.[3]
Das Wurzelsystem ist je nach Standort unterschiedlich. In schweren, feuchten Böden ist das Wurzelsystem weit ausgebreitet mit den meisten Wurzeln in Bodentiefen von 1 bis 1,2 Metern. Auf trockeneren Böden entwickelt die Amerikanische Ulme eine tiefreichende Pfahlwurzel.[3][2]
In Wäldern werden 15 bis 18 Meter lange Stämme gebildet. Freistehende Exemplare weisen Äste ab einer Höhe über dem Grund von 3 bis 6 Metern auf und bilden eine weit ausgebreitete Baumkrone aus.[3] Der Kronendurchmesser kann über 30 Meter betragen.
Die hellbraune bis dunkelgraue Borke ist tief rissig und löst sich in unregelmäßigen Streifen, die sich an ihren Enden zusammenkrümmen, vom Stamm ab.[4][5] Die innere Borke besteht aus abwechselnden braunen und weißen Schichten.[6] Das Holz ist weich.[5] Die Rinde der Zweige ist braun und flaumig behaart bis kahl. Die Äste hängen und ältere Äste sind glatt, nicht geflügelt.[5] Die rot-braunen Winterknospen sind konisch oder schmal-eiförmig mit spitzem oberen Ende und mehr oder weniger flaumig behaart[4] oder kahl[5]. Die Zweige enden mit Blattnarben, die „Endknospe“ sitzt also nicht wirklich endständig (terminal) etwas größer als die seitlichen.[6]
Die wechselständig an den Zweigen angeordneten Laubblätter sind in Blattstiel und Blattspreite gegliedert. Der kahle bis flaumig behaarte Blattstiel ist etwa 5 Millimeter lang. Die einfache Blattspreite ist bei einer Länge von meist 8,6 bis 12,5 (7 bis 14[5]) Zentimetern sowie einer Breite von 3 bis,[5] meist 4,2 bis 7 Zentimetern elliptisch oder manchmal länglich,[4] oval bis länglich-verkehrt-eiförmig[5] mit schiefer Spreitenbasis und spitzem bis zugespitztem oberen Ende.[5][4][7] Die Blattränder sind stark doppelt gesägt.[4][5] Die Blattunterseite einschließlich der Blattadern ist spärlich lang behaart und Haarbüschel befinden sich in den Verzweigungen der Adern.[4] Die Blattoberseite ist kahl bis schuppig.[5] Es liegt Fiedernervatur vor. Die zwei häutigen Nebenblätter fallen früh ab und hinterlassen auf beiden Seiten des Blattes eine kurze Narbe.[5]
Die bündeligen Blütenstände sind kürzer als 2,5 Zentimeter und enthalten drei bis vier Blüten.[4][2] Es sind zwei häutige Tragblättern vorhanden.[5] Die Blüten und Früchte hängen an[5] 7 bis 17 Millimeter langen dünnen Stielen, die sich bis zur Fruchtreife auf maximal 25 Millimeter verlängern.[4][2]
Die Blütenknospen sind kahl.[2] Die meist zwittrigen Blüten besitzen eine einfache Blütenhülle. Die sieben bis neun unscheinbar grün gefärbten und oberhalb ihrer Mitte rot getönten Blütenhüllblätter sind und glockig verwachsen. Der Blütenkelch ist etwas asymmetrisch und endet in sieben bis neun kurzen Kelchlappen; die Ränder sind bewimpert.[5] Es sind sieben bis neun Staubblätter vorhanden. Die Staubfäden sind flach und die Staubbeutel sind leuchtend rot[2].[5] Der Stempel ist hellgrün.[2] Der relativ kurze Griffel endet in einer zweiästigen, weiß bewimperten, tief geteilten Narbe.[5]
Es werden Flügelnüsse (Samara) gebildet. Die bei Reife lohfarbenen oder cremegelben, manchmal rötlich-purpurfaben gefleckten, verdickten Nussfrüchte sind bei einer Länge von 0,9 bis 1,3 Zentimetern sowie einer Breite von 0,6 bis 0,8 Zentimetern elliptisch länglich[4] oder eiförmig[5]; ihre Ränder sind dicht gelb bis weiß bewimpert und ihre Flächen sind kahl.[4] Die häutigen Flügel sind mit etwa 1 Millimetern relativ schmal.[5] Das obere Ende des Flügels ist tief gekerbt.[6]
Die Chromosomengrundzahl beträgt x = 14; es liegt oft Tetraploidie mit der Chromosomenzahl 2n = 56 vor.[5][8] Bei einem kleineren Teil der Populationen liegt Diploidie vor.[9]
Die Blütezeit, Fruchtreife und das Fallen der Diasporen findet im Frühling statt[2][4] und variiert zwischen der Golfküste und Kanada um etwa 100 Tage. Die Blütenknospen schwellen in den Südstaaten früh im Februar und zuletzt im Mai in Kanada an.[3] Die Anthese liegt zwei bis drei Wochen vor der Laubentfaltung. Die Früchte reifen während sich die Laubblätter entfalten oder kurz danach. Die Diasporen werden ausgebreitet sobald die Früchte reif sind und die Ausbreitung ist im Süden Mitte März und im Norden Mitte Juni beendet.[3][2]
Bei Ulmus americana handelt es sich um einen Phanerophyten. Es erfolgt eine vegetative Vermehrung, beispielsweise durch Stockausschlag.[3][2]
Blühfähig sind Exemplare der Amerikanischen Ulme frühestens mit 15 Jahren, aber erst mit 40 Jahren sind sie voll produktiv.[3][2] Die Amerikanische Ulme ist grundsätzlich selbststeril.[2] Fröste im Frühling zerstören Blüten und Früchte.[2]
Die Ausbreitung der Diasporen, es sind die Flügelnüsse (Samara), erfolgt durch den Wind (Anemochorie). Die meisten Diasporen werden nicht weiter als 90 Meter vom Mutterbaum verfrachtet, aber einige werden 400 Meter weit transportiert. Von Exemplaren, die direkt an Fließgewässern stehen werden die Diasporen viele Meilen durch das Wasser ausgebreitet.[3]
Die Keimung der Samen erfolgt epigeal, früh nach der Ausbreitung; aber einige Samen bleiben im Boden keimfähig bis zum darauffolgenden Frühling.[3]
Die Ulmus americana bietet vielen Tieren Nistplätze. Die Blütenknospen, Blüten und Früchte werden von vielen Tieren gefressen.[3][2]
Das ursprüngliche weite Verbreitungsgebiet von Ulmus americana reicht in Nordamerika von den östlichen sowie westlichen kanadischen Provinzen New Brunswick, Ontario, Prince Edward Island, Quebec, Manitoba, Saskatchewan und in den US-Bundesstaaten Montana, Wyoming, Illinois, Iowa, Kansas, Minnesota, Missouri, Nebraska, North Dakota, South Dakota, Oklahoma, Wisconsin, Connecticut, Indiana, Maine, Massachusetts, Michigan, New Hampshire, New Jersey, New York, Ohio, Pennsylvania, Rhode Island, Vermont, West Virginia, Texas, Alabama, Arkansas, Delaware, Florida, Kentucky, Louisiana, Maryland, Mississippi, North Carolina, South Carolina, Tennessee, Virginia, District of Columbia.[1][5][2] In den letzten 100 Jahren ist sie in Idaho verwildert.[1][5]
Sie gedeiht in Auwäldern, Sumpfwäldern, laubabwerfenden Waldländern, entlang von Zäunen, Weideland, alten Feldern und auf Ödland in Höhenlagen von 0 bis 1400 Metern.[5]
Ulmus americana kommt im Gesamtverbreitungsgebiet meist in Ebenen und Tiefländern vor, ist aber nicht nur auf diese Gebiete beschränkt. Sie kommt meist nicht in tiefen Sümpfen vor. In größeren Höhenlagen in the Appalachen kommt sie oft nur in der Nähe großer Ströme vor und selten gedeiht sie in Höhenlagen oberhalb von 610 Metern. Aber in West Virginia gedeiht sie noch in Höhenlagen von 760 Metern. In den Seen- sowie zentralen US-Staatesn gedeiht sie auf Ebenen sowie Moränenhügeln genauso wie im Tiefland und an Sumpfrändern. Entlang des nordwestlichen Verbreitungsgrenze gedeiht sie meist nur auf Talböden entlang von Wasserläufen.[2]
Ulmus americana ist auf vielen Bodentypen zu finden. Sie gedeiht am besten in reichen, gut drainierten Lehmböden. Die Bodenfeuchtigkeit ist für das Wachstum von Ulmus americana entscheidend. Ulmus americana kommt mit unterschiedlichsten Boden-pH-Werten zurecht. An den Sumpfrändern ist der pH-Wert ziemlich sauer und auf Prärie-Böden ist er ziemlich alkalisch. Die pH-Werte reichen im Gesamtverbreitungsgebiet von 5,5 bis 8,0. Die Laubstreu von Ulmus americana zersetzt sich viel schneller als von vielen anderen nordamerikanischen Laubbaumarten. Es werden viele wichtige Nährstoffe dem Boden zur Verfügung gestellt.[2]
Im natürlichen Verbreitungsgebiet von Ulmus americana variiert das Klima von warm und humid im Südosten bis kalt und trocken im Nordwesten. Die Durchschnittstemperaturen reichen: im Januar von −18 °C und darunter in Kanada bis 16 °C in Zentralflorida; im Juli von 16 °C in Manitoba bis 27 °C in den Südstaaten. Das Jahresmaximum liegt zwischen 32 °C bis 35 °C im Nordosten und 38 °C bis 41 °C im Süden sowie Westen. Das Jahresminimum liegt zwischen −40 °C bis −18 °C im Norden und −18 °C bis −1 °C im Süden.[2]
Die Jahresniederschläge variieren von spärlichen 380 mm im Nordwesten bis reichlichen 1520 mm an der Golfküste. Im zentralen Teil des Verbreitungsgebietes liegen die Jahresniederschläge zwischen etwa 760 und 1270 mm im größten Teil des Verbreitungsgebietes erfolgen die Niederschläge hauptsächlich in der warmen Jahreszeit im April bis September. Die jährliche Schneemenge reicht von keinem Schnee in Florida bis 200 cm im Nordosten; wenige Gebiete hauptsächlich um die Großen Seen erhalten 254 bis 380 cm Schnee pro Jahr.[2] Die durchschnittliche frostfreie Periode ist etwa 80 bis 160 Tage im nördlichsten Teil der US-Bundesstaaten und Kanada und etwa 200 bis 320 Tagen an der Golfküste und den Südstaaten.[2]
Die Erstveröffentlichung von Ulmus americana erfolgte 1753 durch Carl von Linné in Species Plantarum, 1, S. 226.[10] Ein Homonym ist Ulmus americana Marshall.[11][1] Synonyme für Ulmus americana L. sind Ulmus americana var. aspera Chapm., Ulmus americana var. floridana (Chapm.) Little, Ulmus floridana Chapm.[5] Es sind keine Subtaxa akzeptiert.
Ulmus americana gehört zur Sektion Blepharocarpus aus der Untergattung Oreoptelea in der Gattung Ulmus innerhalb der Familie Ulmaceae.[1]
Das Holz der Amerikanische Ulme ist grobfaserig, schwer und fest. Es ist nicht haltbar und verzerrt sich und splittert stark beim Trocknen. Das Holz wir zum Herstellen von Kästchen, Kisten, Körben, Fässern, Möbeln, landwirtschaftlichen Geräten und Särgen verwendet. Das Furnier wird für Möbel und Vertäfelungen verwendet. Die Amerikanische Ulme liefert auch Feuerholz.[3]
Die Amerikanische Ulme wird zum Schutz vor Erosion und Windschutz angepflanzt. Das meist flache und weitausgebreitete Wurzelsystem macht die Amerikanische Ulme ziemlich windfest. Die Amerikanische Ulme kann durch Steckhölzer vegetativ vermehrt werden, aber mit mehr oder weniger guten Ergebnissen.[3]
Von den Indianern der südöstlichen Vereinigten Staaten wurde die innere Borke für viele Dekorationszwecke verwendet.[3]
Sie wird als Zierpflanze verwendet.[1] Es gibt einige Sorten und Hybriden. Exemplare der Amerikanischen Ulme säumen viele Straßen[3] und spenden Schatten. Ihre besonders guten Eigenschaften zur Nutzung an Straßen ist das schnelle Wachstum, die Härte und Stresstoleranz.[2]
Die indianischen Ureinwohner nutzten unter anderem die Borke zur Anfertigung von Kanus, Seilen und anderen Gebrauchsgegenständen.
Der Pilz Ceratocystis ulmi breitete sich ab etwa 1930 in den USA aus.[2] Durch den Pilzbefall ist die Population der Amerikanischen Ulme seit 1976 um die Hälfte dezimiert worden. Dieser Pilz verstopft die wasserführenden Gefäße des Baumes, führt zum Verwelken und schließlich Absterben der betroffenen Äste und letztlich des ganzen Baumes. Rindenkäfer verbreiten die Krankheit von Exemplar zu Exemplar. Versprühen von Insektiziden gegen die Käfer ist nur eine vorübergehende Maßnahme. Eine dauerhaft wirkende Behandlung ist zurzeit nicht bekannt. Daher werden die Bestände weiterhin dezimiert werden, zumal die Amerikanische Ulme besonders anfällig ist.
Versuche, diese Anfälligkeit durch Kreuzungen mit anderen Ulmen zu vermeiden, haben bisher noch nicht zu durchschlagenden Erfolgen geführt, weil resistente Arten zugleich mit Nachteilen behaftet sind. Der Sibirischen Ulme beispielsweise fehlt der symmetrische Wuchs und das Holz ist wesentlich brüchiger und splittert leicht.
Gegen das Ulmensterben resistent sind beispielsweise die Sorten ‘Princeton’ und ‘Valley Forge’.[12]
Die Amerikanische Ulme ist der offizielle Staatsbaum der US-Bundesstaaten Massachusetts und North Dakota.[5]
In einigen Gemälden ist die Amerikanische Ulme abgebildet.
Frederick Childe Hassam: „Washington Arch, Spring“ 1893
Frederick Childe Hassam: „Church at Old Lyme“ 1905
Frederick Childe Hassam: „The East Hampton Elms in May“ 1920
George Inness: „Old Elm at Medfield“
Trivialnamen in anderen Sprache sind:[1][5]
Es gibt viele Einzelexemplare der Amerikanische Ulme, die besonders bekannt sind; einige die besonders als alt sind, eine besondere Wuchsform haben, besonders groß sind, einen Namen bekommen haben oder über die eine besondere Geschichte bekannt ist.
Die Amerikanische Ulme (Ulmus americana), auch Weiß-Ulme genannt, ist eine Pflanzenart aus der Gattung der Ulmen (Ulmus) innerhalb der Familie der Ulmengewächse (Ulmaceae). Sie ist in Nordamerika weitverbreitet. Sie wird als Zierpflanze und im Landschaftsbau verwendet. Die Bestände der Amerikanischen Ulme wurden aufgrund des Pilzes Ceratocystis ulmi in der zweiten Hälfte des 20. Jahrhunderts stark dezimiert (Ulmensterben).
In Pāpalōcuahuitl (Ulmus americana, caxtillāntlahtōlli: olmo americano) ca tlanelhuayōtl īpān in cenyeliztli in Ulmaceae tlapēhualtilli tlani in ompa Mēxihco, Ixachitlān Mictlāmpa.
In Pāpalōcuahuitl (Ulmus americana, caxtillāntlahtōlli: olmo americano) ca tlanelhuayōtl īpān in cenyeliztli in Ulmaceae tlapēhualtilli tlani in ompa Mēxihco, Ixachitlān Mictlāmpa.
Homenó'e, hoohtseto-éve.
Homenó'e
Homenó'eo'o.
É-hátaa'êstó'ôheo'o. É-háestaenao'o.
Véhpotôtse.
Véhpotôtse.
Ulmus americana, generally known as the American elm or, less commonly, as the white elm or water elm,[a] is a species of elm native to eastern North America, naturally occurring from Nova Scotia west to Alberta and Montana, and south to Florida and central Texas. The American elm is an extremely hardy tree that can withstand winter temperatures as low as −42 °C (−44 °F). Trees in areas unaffected by Dutch elm disease (DED) can live for several hundred years. A prime example of the species was the Sauble Elm,[3] which grew beside the banks of the Sauble River in Ontario, Canada, to a height of 43 m (140 ft), with a d.b.h of 196 cm (6.43 ft) before succumbing to DED; when it was felled in 1968, a tree-ring count established that it had germinated in 1701.
For over 80 years, U. americana had been identified as 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 USDA 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 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.[4][5]
Ulmus americana was first described and named by Carl Linnaeus in his Species Plantarum, published in 1753. No subspecies or varieties are currently recognized within the species.
The American elm is a deciduous monoecious tree which, before the introduction of DED, commonly grew to more than 100 feet (30 m) tall with a trunk whose diameter at breast height was more than 4 feet (1.2 m), supporting a high, spreading umbrella-like canopy. The leaves are alternate, 7–20 cm long, with double-serrate margins and an oblique base. 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,[6] and emerge in early spring before the leaves. The fruit is a flat samara 2 cm long by 1.5 cm broad, with a circular papery wing surrounding the single 4–5 mm seed. As in the closely related European White Elm Ulmus laevis, 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.[7] Ploidy is 2n = 56, or more rarely, 2n = 28.[8]
U. americana, Toronto, c. 1914
Bark
Boles
Flowers
.jpg)
Leaf
.jpg)
Foliage
Seedlings
The American elm 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.[9] On more elevated terrain, as in the Appalachian Mountains, it is most often found along rivers.[10] The species' wind-dispersed seeds enable it to spread rapidly as suitable areas of habitat become available.[9] 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 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 the first two of these types also occurring in Canada.[11] A sugar maple-ironwood-American elm cover type occurs on some hilltops near Témiscaming, Quebec.[12]
The leaves of the American elm serve as food for the larvae of a number of species of Lepidoptera (see List of Lepidoptera that feed on elms). 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 the Columbian Silkmoth (Hyalophora columbia) and the Banded Tussock Moth (Pale Tiger Moth) (Halysidota tessellaris).[13]
The American elm is highly susceptible to DED and 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,[14] their main impact is as vectors of DED.
American elm is also moderately preferred for feeding and reproduction by the adult elm leaf beetle Xanthogaleruca luteola[15] and highly preferred for feeding by the Japanese beetle Popillia japonica[16] in the United States.
U. americana is also the most susceptible of all the elms to verticillium wilt,[17] whose external symptoms closely mimic those of DED. However, the condition 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.[18] However, in some areas still not infested by DED, 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 the xylem and are thus relatively ineffective.[19]
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 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 the late 1990s.[18]
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 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 a handful of cultivars, causing extremely low genetic diversity.[20] These trees' rapid growth and longevity, leading to great size within decades, made them popular before the advent of DED.[9] 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 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."[9]
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 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 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."[21] The classic vase-shaped elm was mainly the result of selective breeding of a few cultivars and is much less likely to occur in the wild.[22]
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.[23] The tree 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.[24][25] 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 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.[26] American Elms are only rarely found in New Zealand.[27]
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 a momentary lapse from vacuity.[28]
Numerous cultivars have been raised, originally for their aesthetic merit but more recently for their resistance to Dutch elm disease[29] The total number of named cultivars is circa 45, at least 18 of which have probably been lost to cultivation as a consequence of DED or other factors:
and others.[30]
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'.[31] 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.[32]
'Princeton' has been in occasional cultivation since 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 the White House in Washington, D.C. The trees, whose maintenance the National Park Service (NPS) manages, remain healthy and are thriving.[33] 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.[34]
It has also been noted that monoculture plantings of U. americana cultivars, such as those along Pennsylvania Avenue, have disproportionate vulnerabilities to disease.[34] Further, long-term studies of 'Princeton' in Europe and 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, the preferred cultivars of U. americana are 'New Harmony' and 'Princeton'.[35]
'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.[36] The error may still be causing nurseries to sell 'Princeton' elms that are mislabeled as 'Jefferson', although one can distinguish between the two cultivars as the trees mature.[34][37]
In 2007, the 'Elm Recovery Project'[38] 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.[39]
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 the development of DED-resistant strains of American elm trees.[40] 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.[41]
Thousands of attempts to cross the American elm with the Siberian elm U. pumila failed.[42] Attempts at the Arnold Arboretum using ten other American, European and Asiatic species also ended in failure, attributed to the differences in ploidy and operational dichogamy,[6] although the ploidy factor has been discounted by other authorities.[43]
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 the University of Wisconsin–Madison after he overcame the problem of keeping Chinese elm pollen alive until spring.[44] 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 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.[45]
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.[9] Accordingly, the wood originally had few uses, save for making hubs for wagon wheels.[9] 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.[9]
Young twigs and branchlets of the American elm have tough, fibrous bark that has been used as a tying and binding material, even for rope swings for children, and also for making whips.[9]
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 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.[46] The Olmsted-designed park system in Buffalo, NY[47] did not fare as well.
A row of mature American elms lines Central Park along the entire length of Fifth Avenue from 59th to 110th Streets.[48] 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 the largest remaining stand in the country.[49]
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 the campus in recent years.[50]
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 $3M annually to aggressively combat the disease utilizing Dursban Turf[51] and the Dutch Trig vaccine,[52] losing 1500–4000 trees per year.
Governmental agencies, educational institutions or other organizations in most of 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 United States national champion American elm tree is located in Iberville Parish, Louisiana. When measured in 2010, the tree had a trunk circumference of 324 inches (820 cm), a height of 111 feet (34 m) and an average crown spread of 79 feet (24 m).[53]
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 metres (74 ft) and a diameter at breast height of 98 centimetres (39 in) (circumference of 308 centimetres (121 in)) when measured in 2000.[54] The tree replaced on 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 centimetres (45 in) (circumference of 361 centimetres (142 in)).[55]
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 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 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.[56]
The Washington Elm, Cambridge, Massachusetts. George Washington is said to have taken command of the American Continental Army under the Washington Elm in Cambridge on July 3, 1775. The tree survived until the 1920s and "was thought to be a survivor of the primeval forest". In 1872, a large branch fell from it and was used to construct a pulpit for a nearby church.[57] The tree, an American white elm, became a celebrated attraction, with its own plaque, a fence constructed around it and a road moved in order to help preserve it.[58] The tree was cut down (or fell—sources differ) in October 1920 after an expert determined it was dead.
The city of Cambridge had plans for it to be "carefully cut up and a piece sent to each state of the country and to the District of Columbia and Alaska," according to The Harvard Crimson.[59] As late as the early 1930s, garden shops advertised that they had cuttings of the tree for sale, although the accuracy of the claims has been doubted. A Harvard "professor of plant anatomy" examined the tree rings days after the tree was felled and pronounced it between 204 and 210 years old, making it at most 62 years old when Washington took command of the troops at Cambridge. The tree would have been a little more than two feet in diameter (at 30 inches above ground) in 1773.[60]
In 1896, an alumnus of the University of Washington, obtained a rooted cutting of the Cambridge tree and sent it to Professor Edmund Meany at the university. The cutting was planted, cuttings were then taken from it, including one planted on February 18, 1932, the 200th anniversary of the birth of George Washington, for whom Washington state is named. That tree remains on the campus of the Washington State Capitol. Just to the west of the tree is a small elm from a cutting made in 1979.[58]
George Washington's Elm, Washington, D.C. George Washington supposedly had a favorite spot under an elm tree near the United States Capitol Building from which he would watch construction of the building. The elm stood near the Senate wing of the Capitol building until 1948.[57]
The Logan Elm that stood near Circleville, Ohio, was one of the largest American elms in the world. The 65-foot-tall (20 m) tree had a trunk circumference of 24 feet (7.3 m) and a crown spread of 180 feet (55 m).[61] Weakened by DED, the tree died in 1964 from storm damage.[61] The Logan Elm State Memorial commemorates the site and preserves various associated markers and monuments.[61] According to tradition, Chief Logan of the Mingo tribe delivered a passionate speech at a peace-treaty meeting under this elm in 1774.[61][62]
Another notable American elm, named Herbie, was the tallest American elm in New England until it was cut down on January 19, 2010, after it succumbed to DED. Herbie was 110 feet (34 m) tall at its peak and had a circumference of 20.3 feet (6.2 m), or a diameter of approximately 6.5 feet (2.0 m). The tree stood in Yarmouth, Maine, where it was cared for by the town's tree warden, Frank Knight.[63]
When cut down, Herbie was 217 years old. Herbie's wood is of interest to dendroclimatologists, who will use cross-sections of the trunk to help answer questions about climate during the tree's lifetime.[63]
The Glencorradale Elm on Prince Edward Island, Canada, is a surviving wild elm believed to be several hundred years old.[64]
An American elm located in a parking lot directly across the street from the Alfred P. Murrah Federal Building in Oklahoma City survived the Oklahoma City bombing on April 19, 1995, that killed 168 people and destroyed the Murrah building. Damaged in the blast, with fragments lodged in its trunk and branches, it was nearly cut down in efforts to recover evidence. However, nearly a year later the tree began to bloom. Then known as the Survivor Tree, it became an important part of the Oklahoma City National Memorial, and is featured prominently on the official logo of the memorial.[65]
The Parliament Hill Elm was planted in Ottawa, Canada, in the late 1910s or early 1920s when Centre Block was rebuilt following the Great fire of 1916. The tree grew for approximately a century next to a statue of John A. Macdonald and was one of the few in the region to survive the spread of DED in the 1970s and 1980s.[66] Despite protests from Ottawa area environmentalists and resistance from Opposition Members of Parliament the tree was removed in April 2019 to make way for new Centre Block renovations.[67]
Early photos of New England American elms, showing growth patterns, The New International Encyclopædia (1905)
Lafayette Street, Salem, Massachusetts: 'high-tunnel effect' of U. americana avenues, once common in New England (colorized postcard, 1910)
Rows of American elm trees lining the sides of a path traversing the length of the National Mall in Washington, D.C. (April 2010)
Grant Crescent, Griffith, Australian Capital Territory, Australia: American elms in autumn
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Grant Crescent, Griffith, Australian Capital Territory, Australia: American elms in winter
Ulmus americana as campus elm: Cambridge, Massachusetts
American elm, Old Deerfield, Massachusetts (2011). Girth was 19.3 ft at 4.5 ft above ground; height 106.8 ft; avg. crown spread 105 ft. This tree died in 2017.
Same American elm, Old Deerfield, Massachusetts (2012). This tree died in 2017.
Surviving American elm "street tree" in western Massachusetts (2016)
Another view of the previous "street tree" in western Massachusetts (August 2020)
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American elm, Hatfield, Massachusetts (2020). Measurements as of November 2019: girth 17.5 ft, 11 in at 4.5 ft above ground; height 86 ft; spread 87 ft.
American Elm in Massachusetts (June 2012). Girth 18 ft at 4.5 ft above ground; est. height 80 ft; spread 100 ft.
"The Grayson Elm" in Amherst, Massachusetts, in winter. American elm, Massachusetts (2013), with octopus-like limbs. Girth 17 ft; height 80 ft.
"The Grayson Elm" in Amherst, Massachusetts, in summer (2017)
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"The Grayson Elm" in Amherst, Massachusetts, in fall (2020)
Large American elm located at Smith College in Northampton, Massachusetts (2023)
American Elm in Johnstown, New York (2013). 199 inches in circumference and 90 feet tall. Now deceased.
American elm, Spring Grove Cemetery, Hartford, Connecticut (2012). Girth 15 ft at 4.5 ft above ground; height 83 ft; spread 75 ft. This tree died in 2021 due to Dutch Elm disease.
American elms, Central Park, Manhattan, New York City (Spring 2011)
Large American elm in New Haven, Connecticut (June 2017). Girth over 18.5 ft; height 88 ft; spread 95 ft. This tree died in 2019.
West Hartford Elm - Large American elm in West Hartford, Connecticut (May 2017). Girth 16 ft, 3 inches at 4.5 ft above ground; height 74 ft; spread 97 ft.
![American elm in Charlottetown, Prince Edward Island, Canada (August 2019). This tree was downed by Hurricane Fiona in 2022.[68]](http://en.wikipedia.org/wiki/File:American_Elm_Tree,_Charlottetown,_PEI_-_August_2019.jpg)
American elm in Charlottetown, Prince Edward Island, Canada (August 2019). This tree was downed by Hurricane Fiona in 2022.[68]
Old American elm in Halifax Public Gardens, Nova Scotia, Canada (August 2019)
Elm tree on Elm Street in Plaistow, New Hampshire, which was planted in the late 1800s (August 2019). Girth 13 ft at 4.5 ft above ground; height 85 ft; spread 80 ft.
Elm tree in Vermont (June 2023). Measurements from June 2017: Girth 13 ft at 4.5 ft above ground; height 70 ft; spread 75 ft.
American elm in front of the Florence K. Murray Courthouse in Newport, Rhode Island (August 2015)
Ulmus americana (American elm) at Longwood Gardens, Kennett Square, Pennsylvania (May 2004)
![American elm at Dartmouth College in Hanover, New Hampshire (June 2015) This tree was cut down in 2022 due to Dutch Elm disease.[69]](http://en.wikipedia.org/wiki/File:American_Elm,_Dartmouth_College,_Hanover,_NH_(June_2015).jpg)
American elm at Dartmouth College in Hanover, New Hampshire (June 2015) This tree was cut down in 2022 due to Dutch Elm disease.[69]
American elm in Greenwich, CT (May 2019)
American elm at Milk Row Cemetery in Somerville, MA (August 2019)
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American elm near the Woodstock, CT, fairgrounds (May 2020)
American elm located at the Hill-Stead Museum in Farmington, Connecticut (August 2021)
American elm in Connecticut (May 2020)
American elm at Phillips Academy, Andover, MA (May 2020)
American elm tree, which survived the tornado that touched down in Springfield, Massachusetts, in 2011 (June 2020)
American elm tree in Cummington, Massachusetts (August 2020)
American elm tree in Adams, Massachusetts (August 2020)
American elm tree in a park in Pittsfield, Massachusetts (August 2020)
American elm tree located in Charlemont, Massachusetts (July 2021)
American elm tree in Sunderland, Massachusetts (June 2022)
Alley of American elms, some from 1881,[70] lining the central walk through The Oval on the campus of Colorado State University, Fort Collins (May 2004)
American Elm Tree in Easthampton, MA (August 2022). Across the street, from the park, in the rotary in which stood the "Pulpit Elm" until 1952.
Phillips Academy Elm, Andover, MA (November 2019)
New York City's Central Park is home to approximately 1,200 American elms. The oldest of these elms were planted during the 1860s by Frederick Law Olmsted, making them among the oldest stands of American elms in the world. The trees are particularly noteworthy along the Mall and Literary Walk, where 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.[71]
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 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.[72]
Several rows of American elm trees that the National Park Service first planted during the 1930s line much of the 1.9 miles (3.0 km) length of the National Mall in Washington, D.C. DED first appeared on 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 a result, the population of American elms planted on the Mall and its surrounding areas has remained intact for more than 80 years.[73]
The nobility and arching grace of the American Elm in its heyday, on farms, in villages, in towns and on campuses, were celebrated in the books of photographs of Wallace Nutting (Massachusetts Beautiful, N.Y. 1923, and other volumes in the series) and of Samuel Chamberlain (The New England Image, New York, 1962). Frederick Childe Hassam is notable among painters who have depicted American Elm.
![Scribner's magazine [1887]](http://en.wikipedia.org/wiki/File:Scribner%27s_magazine_(1887)_(14778695871).jpg)
Scribner's magazine [1887]
![Frederick Childe Hassam, 'Washington Arch, Spring' [1893]](http://en.wikipedia.org/wiki/File:Hassam_Washington_Arch_Spring.jpg)
Frederick Childe Hassam, 'Washington Arch, Spring' [1893]
![Frederick Childe Hassam, 'Church at Old Lyme' [1905]](http://en.wikipedia.org/wiki/File:Church_at_Old_Lyme_Childe_Hassam.jpeg)
Frederick Childe Hassam, 'Church at Old Lyme' [1905]
![Frederick Childe Hassam, 'The East Hampton Elms in May' [1920]](http://en.wikipedia.org/wiki/File:Childe_Hassam%27s_1920_oil,_The_East_Hampton_Elms_in_May.jpg)
Frederick Childe Hassam, 'The East Hampton Elms in May' [1920]
George Inness, 'Old Elm at Medfield'
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American elm avenue, New Haven, Connecticut (1901), Thomas Meehan and Sons catalogue
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{{cite journal}}: CS1 maint: multiple names: authors list (link)|volume= / |date= mismatch 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, naturally occurring from Nova Scotia west to Alberta and Montana, and south to Florida and central Texas. The American elm is an extremely hardy tree that can withstand winter temperatures as low as −42 °C (−44 °F). Trees in areas unaffected by Dutch elm disease (DED) can live for several hundred years. 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 d.b.h of 196 cm (6.43 ft) before succumbing to DED; when it was felled in 1968, a tree-ring count established that it had germinated in 1701.
For over 80 years, U. americana had been identified as 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 USDA 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 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, el Olmo americano u Olmo blanco, es una especie de árbol perteneciente a la familia de las ulmáceas.
Es originaria del este de Norteamérica, que va desde Nueva Escocia al oeste hasta llegar a la Columbia Británica, desde el norte de Alberta en el extremo de su zona de distribución, al sur hasta Florida y el centro de Texas. Es un árbol extremadamente duro que puede soportar temperaturas invernales de hasta −42 °C. Árboles en zonas no afectadas por la grafiosis pueden vivir durante varios cientos de años. Un ejemplo destacado de la especie es el Olmo de Sauble, [1], que crecía en Ontario, Canadá, hasta una altura de 43 m, con un diámetro de 196 cm antes de sucumbir a la grafiosis. Cayó en 1968 y el recuento de sus anillos estableció que había germinado en 1703.
El olmo americano es un árbol caducifolio, que, antes de la llegada de la grafiosis, usualmente crece hasta> 30 m de alto con un tronco de> 1,2 m de diámetro.
La corona forma una copa alta y que se dispersa con un amplio espacio de aire por debajo. Las hojas son alternas, 7–20 cm de largo, con bordes doble serrados y una base oblicua. El árbol es hermafrodita, teniendo flores perfectas, (esto es, con partes tanto femeninas como masculinas) y es por lo tanto capaz de autopolinizarse. Las flores son pequeñas, de color pardo purpúreo, y al ser polinizadas por vía aérea, son apétalas; surgen a principios de la primavera, antes de que salgan las hojas. El fruto es una sámara plana de 2 cm de largo y 1,5 cm de ancho, con un ala circular rodeando la simple semilla de 4–5 mm.
Como la especie europea emparentada, olmo temblón (U. laevis), las flores y las semillas surgen en tallos de 1–3 cm de largo. El olmo americano es en conjunto insensible a la longitud de la luz del día (fotoperíodo), y seguirá creciendo bien en otoño hasta que lo lesione la helada.[2] El árbol alcanza la madurez sexual alrededor de los 150 años de edad y es único dentro del género por ser tetraploide, esto es tiene el doble del número normal de cromosomas. Sin embargo, actualmente es infrecuente que el árbol alcance los cien años de edad, debido a su susceptibilidad a la grafiosis. El olmo americano es el árbol del estado de Massachusetts y el de Dakota del Norte.
Ulmus americana fue descrito por Carlos Linneo y publicado en [[Species Plantarum 1: 226. 1753.[3]
Ulmus: nombre genérico que es el nombre clásico griego para el olmo.[4]
americana: epíteto geográfico que alude a su localización en América.
Ulmus americana, el Olmo americano u Olmo blanco, es una especie de árbol perteneciente a la familia de las ulmáceas.
Amerikar zumarra (Ulmus americana) hosto-erorkorreko zuhaitza da, 43 m-rainoko altuera izan dezakeena. Ekialdeko Ipar Amerikan du jatorria.
U. americana zumarren generoan espezie bakarra da, tretaploide edo kromosoma bikoizduna (2n = 56) delako[1].
Amerikar zumarra (Ulmus americana) hosto-erorkorreko zuhaitza da, 43 m-rainoko altuera izan dezakeena. Ekialdeko Ipar Amerikan du jatorria.
U. americana zumarren generoan espezie bakarra da, tretaploide edo kromosoma bikoizduna (2n = 56) delako.
Ulmus americana
L'Orme d'Amérique ou Orme américain (Ulmus americana) est un orme qui pousse notamment dans la vallée du Mississippi, en Nouvelle-Angleterre et dans l'est du Canada, jusqu'au 48e parallèle environ. Il est un des plus grands feuillus de l'est de l'Amérique du nord, il culmine à 35 mètres de haut. Il a une forme facile à identifier, en forme d'urne, avec un tronc long élancé, même en plein champ. C'est l'un des symboles de l’État de Massachusetts aux États-Unis d'Amérique. On appelle aussi cette espèce, Orme blanc[1].
La survie de l'Orme d'Amérique est gravement menacée par la graphiose de l'orme, infection par un myco-parasite introduit au XXe siècle aux États-Unis, à tel point que les biologistes s'attendent à la disparition totale prochaine de l'espèce dans son habitat. Ce parasite provient d'Asie, il a aussi envahi l'Europe où il a décimé les populations d'ormes indigènes.
Ulmus americana
L'Orme d'Amérique ou Orme américain (Ulmus americana) est un orme qui pousse notamment dans la vallée du Mississippi, en Nouvelle-Angleterre et dans l'est du Canada, jusqu'au 48e parallèle environ. Il est un des plus grands feuillus de l'est de l'Amérique du nord, il culmine à 35 mètres de haut. Il a une forme facile à identifier, en forme d'urne, avec un tronc long élancé, même en plein champ. C'est l'un des symboles de l’État de Massachusetts aux États-Unis d'Amérique. On appelle aussi cette espèce, Orme blanc.
Hvítálmur (fræðiheiti: Ulmus americana) er álmtegund sem er ættuð frá austurhluta Norður-Ameríku, frá Nova Scotia vestur til Alberta og Montana, og suður til Florida og mið Texas. Hann er mjög harðgerður og þolir niður að −42 °C. Tré á svæðum sem hafa ekki orðið fyrir barðinu á „hollenskri álmsýki“ geta orðið mörg hundruð ára gömul.[2][3]
Lengst af, eða í 80 ár, hefur U. americana verið talinn fjórlitna (þ.e. með tvöfaldan venjulegan fjölda litninga, 2n=56), sem er óvenjulegt innan ættkvíslarinnar. Hinsvegar hefur rannsókn sem var gerð 2011 af Agricultural Research Service hjá USDA sýnt að um 20% villtra hvítálma eru tvílitna (2n=28)[4] og gætu eins verið í raun önnur tegund. Að auki eru nokkkur þrílitna tré í ræktun og hafa þau sýnt nokkuð þol gegn hollensku álmveikinni[5][6]
Hvítálmur getur orðið um 30m hár og 152 sm í þvermál. Hann er hraðvaxta í æsku og byrjar snemma að fella fræ. Hann stýrist ekki af daglengd og vex fram í fyrstu frost.[7]
Ulmus americana var fyrst lýst og nefndur af Carl Linnaeus í riti hans Species Plantarum, útgefnu 1753. Engar undirtegundir eða afbrigði eru viðurkennd. Illa hefur gengið að blanda honum við aðrar tegundir.[8]
U. americana, Toronto, c.1914
Börkur
Blað
Blöð
Smáplöntur
Hvítálmur (fræðiheiti: Ulmus americana) er álmtegund sem er ættuð frá austurhluta Norður-Ameríku, frá Nova Scotia vestur til Alberta og Montana, og suður til Florida og mið Texas. Hann er mjög harðgerður og þolir niður að −42 °C. Tré á svæðum sem hafa ekki orðið fyrir barðinu á „hollenskri álmsýki“ geta orðið mörg hundruð ára gömul.
Lengst af, eða í 80 ár, hefur U. americana verið talinn fjórlitna (þ.e. með tvöfaldan venjulegan fjölda litninga, 2n=56), sem er óvenjulegt innan ættkvíslarinnar. Hinsvegar hefur rannsókn sem var gerð 2011 af Agricultural Research Service hjá USDA sýnt að um 20% villtra hvítálma eru tvílitna (2n=28) og gætu eins verið í raun önnur tegund. Að auki eru nokkkur þrílitna tré í ræktun og hafa þau sýnt nokkuð þol gegn hollensku álmveikinni
Hvítálmur getur orðið um 30m hár og 152 sm í þvermál. Hann er hraðvaxta í æsku og byrjar snemma að fella fræ. Hann stýrist ekki af daglengd og vex fram í fyrstu frost.
L'olmo americano (Ulmus americana L.) è un albero appartenente alla famiglia Ulmaceae[2] diffuso principalmente nella valle del Mississippi, in Nuova Inghilterra e nell'est del Canada, fino al 48º parallelo circa. È uno dei simboli dello stato del Massachusetts.
La sopravvivenza dell'olmo americano è minacciata dalla grafiosi dell'olmo, un'infezione causata da un fungo parassita originario dell'Europa e introdotto negli USA nel ventesimo secolo, diffuso a tal punto che i biologi prevedono la sparizione della specie dal suo habitat. Tale fungo è endemico della specie europea dell'olmo, la quale vi ha sviluppato resistenza.
L'olmo americano (Ulmus americana L.) è un albero appartenente alla famiglia Ulmaceae diffuso principalmente nella valle del Mississippi, in Nuova Inghilterra e nell'est del Canada, fino al 48º parallelo circa. È uno dei simboli dello stato del Massachusetts.
Ulmus americana (Anglice: usitate American elm; minus commune white elm et water elm) est species florens familiae Ulmacearum, in Americá Septentrionali endemica, a Nová Scotiá occidentem versus ad Columbiam Britannicam, ab Albertá septentrionali meridiem versus ad Floridam et Texiam mediam.
Planta est arbor robustissima, quae temperaturas hiemales sub -42 °C resistere potest. Arbores in regionibus ubi abest Hollandicus ulmorum morbus nonnulla centena annorum vivere possunt.
Notissimum speciei exemplar fuit ulmus in oppido Sauble Ontarionis [4], quae ad 43 m alta crevit, diametro altitudinis pectoris (terminus technicus, Anglice diameter at breast height, d.b.h.) 196 cm ante annum 1968, cum Hollandico ulmorum morbo succubuit. Computatio anulorum arboreorum monstravit eam germinavisse anno 1701.
Ulmus americana est arbor decidua, quae, antequam apparuit Hollandicus ulmorum morbus, commune ad plus quam 30 m alta crescit, trunco plus quam 1.2 m lata (diametro altitudinis pectoris). Corona aulaeum altum extendentem format. Folia sunt alterna, 7–20 cm longa, marginibus duplice serratis et fundamento obliquo. Arbor est hermaphroditica, flores perfectos (h.e. partibus maribus et femineis) habens, et ergo se pollinare potest. Flores sunt parvi, et, quod a vento pollinantur, apetalosi; emergunt primo vere, ante folia. Fructus est plana samara, 2 cm longa et 1.5 cm lata, alá circulari singulum semen 4–5 mm cingente. Sicut in arte cognata Ulmo laevi, flores et semina in caulibus 1–3 cm longis feruntur.
Ulmus americana est unica species intra genus pro tetraploidia (h.e. habens bis usitatum chromosomatum numerum, 2n = 56); ea etiam est protogynosa, et se pollinari est communis.[1]
Cortex Ulmi americanae
Folia Ulmi americanae
Larvae variorum lepidopterorum foliis Ulmi americanae vescuntur. Vide Indicem Lepidopterorum quae ulmis vescuntur.
U. americana Hollandicum ulmorum morbum et flavos ulmorum (Anglice: elm yellows) haud resistit. Ea etiam praeponitur pro victu reproductioneque a Xanthogaleruca luteola adulto[2][3], et maxime praeponitur pro victu a Popillia japonica.[4][5]
Monumentum in Ohio Ulmum americanam memorat quae apud situm stabat ubi, anno 1774, Princeps Logan tribus Mingo orationem vehementem habuit, celeberrimam ab Indigena Americano habitam orationem.
Una ex maximis ulmis in CFA notis, arbor 20 m alta, folia habebat quae 55 m lata extenderunt, trunco 7.3 m lato. Haec ulmus anno 1964 Hollandico ulmorum morbo detrimentoque tempestatis periit.
Alia notabilis Ulmus americana, "Herbie" appellata, fuit altissima in Nová Angliá Ulmus americana donec die 19 Ianuarii 2010, cum homines eam caderent ob Hollandicum ulmorum morbum. Herbie fuerat 34 m alta, circumferentia 6.2 m, diametro circa 2.0 m. Arbor Yarmouth in urbe Cenomannicae stabat, ubi Franciscus Knight, urbanus arborum custos, eam excolebat.[6]
Herbie novissime mortua fuit 217 annos nata.
Haec stipula ad biologiam spectat. Amplifica, si potes! Ulmus americana (Anglice: usitate American elm; minus commune white elm et water elm) est species florens familiae Ulmacearum, in Americá Septentrionali endemica, a Nová Scotiá occidentem versus ad Columbiam Britannicam, ab Albertá septentrionali meridiem versus ad Floridam et Texiam mediam.
Planta est arbor robustissima, quae temperaturas hiemales sub -42 °C resistere potest. Arbores in regionibus ubi abest Hollandicus ulmorum morbus nonnulla centena annorum vivere possunt.
Notissimum speciei exemplar fuit ulmus in oppido Sauble Ontarionis [4], quae ad 43 m alta crevit, diametro altitudinis pectoris (terminus technicus, Anglice diameter at breast height, d.b.h.) 196 cm ante annum 1968, cum Hollandico ulmorum morbo succubuit. Computatio anulorum arboreorum monstravit eam germinavisse anno 1701.
Kvitalm (Ulmus americana) er et løvfellende tre i almefamilien. Den er utbredt i sentrale og østlige deler av Nord-Amerika. Det blir 21–35 m høyt. Kronen har vidt utsperrete, buete greiner. Barken er lysebrun til grå med grove ribber. Bladene er 10–15 cm lange, egg- til lansettformete, dobbelttannede og svært asymmetriske ved basis.
Kvitalm vokser i mange klimatyper og på ulike sorter jordsmonn. Rene bestander er ikke vanlige, men arten inngår i mange typer blandet skog. Den vokser sammen med svartask, rødlønn, balsampoppel, balsamgran, gulbjørk, sølvlønn, amerikaplatan, sumpeik, borreeik, pileik, vasseik og andre eikearter, virginiapoppel, sukkerbjørk, papirbjørk, svartgran, kvitask, andre almearter, sumptre, canadahemlokk, ambratre, grønnask, amerikanesletre, Celtis laevigata, asklønn og pecantre.
Utbredelsen strekker seg fra Cape Breton i Nova Scotia, vestover til sentrale Ontario, sørlige Manitoba og sørøstlige Saskatchewan, sørover til østligste Montana, nordøstlige Wyoming, vestlige Nebraska, Kansas og Oklahoma inn i sentrale Texas, østover til sentrale Florida og nordover langs østkysten.
Kvitalm var et svært vanlig gatetre i amerikanske byer, men almesyken har drept mange trær.
Bark
Bladverk
Høstfarge
Frø
Kvitalm (Ulmus americana) er et løvfellende tre i almefamilien. Den er utbredt i sentrale og østlige deler av Nord-Amerika. Det blir 21–35 m høyt. Kronen har vidt utsperrete, buete greiner. Barken er lysebrun til grå med grove ribber. Bladene er 10–15 cm lange, egg- til lansettformete, dobbelttannede og svært asymmetriske ved basis.
Kvitalm vokser i mange klimatyper og på ulike sorter jordsmonn. Rene bestander er ikke vanlige, men arten inngår i mange typer blandet skog. Den vokser sammen med svartask, rødlønn, balsampoppel, balsamgran, gulbjørk, sølvlønn, amerikaplatan, sumpeik, borreeik, pileik, vasseik og andre eikearter, virginiapoppel, sukkerbjørk, papirbjørk, svartgran, kvitask, andre almearter, sumptre, canadahemlokk, ambratre, grønnask, amerikanesletre, Celtis laevigata, asklønn og pecantre.
Utbredelsen strekker seg fra Cape Breton i Nova Scotia, vestover til sentrale Ontario, sørlige Manitoba og sørøstlige Saskatchewan, sørover til østligste Montana, nordøstlige Wyoming, vestlige Nebraska, Kansas og Oklahoma inn i sentrale Texas, østover til sentrale Florida og nordover langs østkysten.
Kvitalm var et svært vanlig gatetre i amerikanske byer, men almesyken har drept mange trær.
Ameriški brest (znanstveno ime Ulmus americana) je predstavnik brestov, ki izvorno raste na vzhodu Severne Amerike. Zraste do več kot 30 m visoko in ima dežnikasto krošnjo.
Bližnji sorodnik je dolgopecljati brest iz Evrope.
Vrsta je nekoč obilno preraščala poplavne ravnice severovzhodnega dela Združenih držav Amerike, v prvi polovici 20. stoletja pa jo je zdesetkala holandska bolezen brestov, ki še vedno ogroža sestoje, zato velja ameriški brest za ogroženo vrsto. Mlajša drevesa so odpornejša na bolezen in se razmnožujejo preden dosežejo polno velikost ter podležejo, tako da neposredne nevarnosti za izumrtje ni, so pa preživeli primerki občutno manjši.[1]
Ameriški brest (znanstveno ime Ulmus americana) je predstavnik brestov, ki izvorno raste na vzhodu Severne Amerike. Zraste do več kot 30 m visoko in ima dežnikasto krošnjo.
Bližnji sorodnik je dolgopecljati brest iz Evrope.
Vrsta je nekoč obilno preraščala poplavne ravnice severovzhodnega dela Združenih držav Amerike, v prvi polovici 20. stoletja pa jo je zdesetkala holandska bolezen brestov, ki še vedno ogroža sestoje, zato velja ameriški brest za ogroženo vrsto. Mlajša drevesa so odpornejša na bolezen in se razmnožujejo preden dosežejo polno velikost ter podležejo, tako da neposredne nevarnosti za izumrtje ni, so pa preživeli primerki občutno manjši.
Ulmus americana là một loài thực vật có hoa trong họ Ulmaceae. Loài này được Carl von Linné miêu tả khoa học đầu tiên năm 1753.[2]
Bài viết liên quan đến bộ Hoa hồng này vẫn còn sơ khai. Bạn có thể giúp Wikipedia bằng cách mở rộng nội dung để bài được hoàn chỉnh hơn. Ulmus americana là một loài thực vật có hoa trong họ Ulmaceae. Loài này được Carl von Linné miêu tả khoa học đầu tiên năm 1753.
Ulmus americana L.
Ареал
Вяз американский (лат. Ulmus americana) — лиственное дерево, вид рода Вяз (Ulmus) семейства Вязовые (Ulmaceae).
В Европу интродуцирован в 1752 году, но широкого применения не имеет, так как в сравнении с местными видами ценными качествами не обладает. В России известен единичными экземплярами в Москве, Орловской и Воронежской областях (Каменная Степь).
В природе ареал вида охватывает Северную Америку — от Нью-Брансуика и Манитобы (Канада) на севере до Флориды и Техаса (США) на юге[2].
Растёт в широколиственных лесах на влажных почвах вдоль рек и ручьев, но встречается и на сухих местоположениях. Произрастает на подзолистых почвах и на чернозёмах. Морозостоек.
Дерево высотой до 20—30, иногда до 40, м, с широко-цилиндрической кроной, образованой ветвями, восходящими под острым углом, и наружными свисающими побегами. Кора светло-серая, чешуйчатая. Молодые веточки слегка опушённые.
Почки яйцевидные или притуплённые. Листья продолговато-яйцевидные, длиной 5—10 (до 15) см, остроконечные, у основания неравнобокие, по краю двоякозубчатые, сверху голые или шершавые, снизу почти голые или опушённые, на черешках длиной 5—8 мм.
Цветоножки длиной 1—2 см. Цветки с 7—8, выдающимися из околоцветника, тычинками и белым рыльцем.
Плод эллиптический, по краю ресничатый, с выемкой крыла, достигающей орешка.
Цветение в марте — апреле. Плодоношение в мае.
Живёт до 200 лет.
Вид Вяз американский входит в род Вяз (Ulmus) семейства Вязовые (Ulmaceae) порядка Розоцветные (Proteales).
Вяз американский (лат. Ulmus americana) — лиственное дерево, вид рода Вяз (Ulmus) семейства Вязовые (Ulmaceae).
В Европу интродуцирован в 1752 году, но широкого применения не имеет, так как в сравнении с местными видами ценными качествами не обладает. В России известен единичными экземплярами в Москве, Орловской и Воронежской областях (Каменная Степь).
美国榆（学名：Ulmus americana），或譯美洲榆，为榆科榆属下的一种原產於北美洲東部的喬木。這種樹特別耐寒，可忍受低至零下42攝氏度的低溫，而其壽命也可達數百年。[2][3]
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