Ulmus minor | |
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Field elm, Blismes, Nièvre, France. | |
Scientific classification | |
Kingdom: | Plantae |
Clade: | Tracheophytes |
Clade: | Angiosperms |
Clade: | Eudicots |
Clade: | Rosids |
Order: | Rosales |
Family: | Ulmaceae |
Genus: | Ulmus |
Species: | U. minor |
Binomial name | |
Ulmus minor | |
Distribution map | |
Synonyms | |
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Ulmus minor Mill. , the field elm, is by far the most polymorphic of the European species, although its taxonomy remains a matter of contention. Its natural range is predominantly south European, extending to Asia Minor and Iran; its northern outposts are the Baltic islands of Öland and Gotland, [2] although it may have been introduced by humans. The tree's typical habitat is low-lying forest along the main rivers, growing in association with oak and ash, where it tolerates summer floods as well as droughts. [3]
Current treatment of the species owes much to Richens, [4] who noted (1983) that several varieties of field elm are distinguishable on the European mainland. Of these, he listed the small-leaved U. minor of France and Spain; the narrow-leaved U. minor of northern and central Italy; the densely hairy leaved U. minor of southern Italy and Greece; the U. minor with small-toothed leaves from the Balkans; the U. minor with large-toothed leaves from the Danube region; and the small-leaved U. minor from southern Russia and Ukraine. [5] As for British varieties, "the continental populations most closely related [to eastern English Field Elm] are in central Europe", while south-western forms were introduced from France. [6] He concluded, however, that owing to incomplete field-research at the time of writing, it was "not possible to present an overall breakdown of the European Field Elm into regional varieties". [7] The epithet 'red' elm was commonly used by British foresters, an allusion to the colour of the timber. [8]
Richens sank a number of British elms, notably English elm, as either subspecies or varieties of U. minor in 1968. However, Melville, [9] writing ten years later, identified five distinct species (including U. glabra in the count), several varieties and numerous complex hybrids. In 1992 Armstrong [10] identified no fewer than forty British species and microspecies. Clive Stace (1997) wrote of the British elms "The two-species (glabra and minor) concept of Richens is not sufficiently discriminating to be of taxonomic value". Nevertheless, it is Richens’ classification which has been the most commonly adopted in recent years, although it is not used in Flora Europaea. [11] [12]
In 2009 Dr Max Coleman of the Royal Botanic Garden, Edinburgh wrote: "The advent of DNA fingerprinting has shed considerable light on the question. A number of studies have now shown that the distinctive forms Melville elevated to species and Richens lumped together as field elm are single clones, all genetically identical, which have been propagated by vegetative means such as cuttings or root suckers. This means that enigmatic British elms such as Plot elm and English elm have been shown to be single clones of field elm. Although Richens did not have the evidence to prove it, he was correct in recognising a series of clones and grouping them together as a variable species." [13]
It is hoped that analysis of molecular markers will ultimately eliminate the taxonomic confusion.
The tree typically grows to < 30 m (98 ft) and bears a rounded crown. [14] The bark of the trunk is rough, furrowed lightly in older trees to form a block pattern. Young branchlets occasionally have corky wings. The shoots are slender compared with those of wych elm. The leaves are smaller than those of the other European species, hence the specific epithet minor, however they can vary greatly according to the maturity of the tree. Leaves on juvenile growth (suckers, seedlings etc.) are coarse and pubescent, whereas those on mature growth are generally smooth, though remaining highly variable in form; there are generally fewer than 12 pairs of side veins. [15] A common characteristic is the presence of minute black glands along the leaf veins, detectable with the aid of a magnifying glass. [3] The samarae are oval or obovate, glabrous, 12–15 mm (15⁄32–19⁄32 in) long, notched at the top, with the seed close to the notch. [16] Ulmus minor in France generally begins to flower and fruit when aged 10 years. [17]
The species readily produces suckers from roots and stumps, even after devastation by Dutch elm disease; consequently genetic resources are not considered endangered. [18]
The species has a hugely variable reaction to Dutch elm disease (DED), including all the fashionable pre-20th century plantsman's clones (see Subspecies and varieties). However, field elm is genetically highly variable; Italian specimens when inoculated with the pathogen displayed between 15 and 100% dieback and between 70 and 100% wilting, whereas with trees tested in Spain, the variability ranged from 5 to 100% dieback, and 20 to 95% wilting. [19] In 2013 researchers at the Universidad Politėcnica de Madrid announced the discovery and cloning of trees in Spain with levels of resistance greater than 'Sapporo Autumn Gold' [20] (see Cultivation).
Tolerance of elm yellows (phloem necrosis) is generally good, U. minor exhibiting symptoms such as the 'witch's broom' only sporadically throughout Italy, including Sicily and Sardinia, however the disease was often locally common within the species in France, including Paris. [21]
U. minor in general and a number of clones in particular (see 'Cultivars' below) were once commonly cultivated across Europe in town and country, but owing to its susceptibility to Dutch elm disease, U. minor is now uncommon in cultivation. However, in an ongoing project that began in the 1990s, several thousand surviving field elms have been tested for innate resistance by national research institutes in the EU, with a view to returning field elm to cultivation. [19] Results from Spain (2013), for example, confirm that a very small number of surviving field elms (about 0.5% of those tested) appear to have comparatively high levels of tolerance of the disease, and it is hoped that a controlled crossing of the best of these will produce resistant Ulmus minor hybrids for cultivation. [22]
In the UK, despite its late leaf-flush in the north and its suckering habits, continental U. minor was occasionally planted as an ornamental urban tree. Augustine Henry wrote in 1913 that the U. minor planted in parks in Scotland were of French origin. [23] More recently U. minor seed was imported to the UK from Italy. [24] There are mature survivors in Edinburgh that are not the common U. minor cultivars (2015). [25]
U. minor has been introduced to the southern hemisphere, notably Australasia and Argentina. [26]
U. minor can live to a great age. An ancient field elm stood until recently in the village square of Metaxades, Thrace, Greece. Having abandoned their original village in 1286 after cholera outbreaks, the villagers re-founded it in the hills where a young elm was growing beside a spring. An elm (reputedly the original) and the fountain were the focal-point of the village until the late 20th century. [27] The tallest recorded field elms in Greece were two specimens planted in 1650 beside the newly built church of the Archangels Michael and Gabriel, in Omali Voiou (Oμαλή Bοΐου) near Siatista, which, despite being open-grown trees, attained a height of 40 metres by the mid-20th century. [28] The immemorial elm opposite the village square of Aidona in Thessaly, Greece [29] [30] which has been "listed" as a national "Monument of Nature", [31] lost its crown in a recent storm (2009) and has now been pollarded; it is regenerating vigorously. A rare example of a centuries-old field elm that retains its heartwood and crown is the 360-year-old specimen in the village square of Strinylas, Corfu. [32] [33] [34]
A tree said to be of similar age (200 cm d.b.h.) still stands (2013) in the city of Sliven, Bulgaria; other veterans are said to survive in the village of Samuilovo, 7 km from Sliven. [35] [36] [37]
In France, a tree reputedly over 650 years old survived in the centre of Biscarrosse south of Bordeaux until the summer of 2010, when it finally succumbed to Dutch elm disease. [38] Another veteran with a 6-metre girth survives at Bettange, France, close to the Belgian border, reputedly planted in 1593. [39] Other wrecks include 'l'ormeau de Sully' in Villesèquelande near Carcassonne, [40] "a magnificent tree supported by three metal props", said to have been planted in the early 17th C by the Duc de Sully, [41]
A tree approximately 400 years old and 5.55 metres in girth grows in the town of Mergozzo in Piedmont, Italy. 'L'olmo di Mergozzo', like its French counterparts 'l'orme de Biscarosse' and 'l’orme de Bettange', is hollowed out by age, its life prolonged by lopping, while in Spain the elm in the Plaza del Olmo ("Elm square" in Spanish) in Navajas, Valencia, is 6.3 metres in girth; planted in 1636 it features on the town crest. [42]
In England, large specimens once identified as U. minor subsp. minor, the narrow- or smooth-leafed elm, were once commonplace in the eastern counties before the advent of DED. The largest recorded tree in the UK grew at Great Amwell, Hertfordshire, measuring 40 m in height and 228 cm d.b.h. in 1911. [43] Another famous specimen was the great elm that towered above its two siblings at the bottom of Long Melford Green, Long Melford, Suffolk, [44] till the group succumbed to disease in 1978. The three "were survivors of a former clone of at least nine elms, one dating from 1757". [45] The Long Melford elms were painted in 1940 by the watercolourist S. R. Badmin in his 'Long Melford Green on a Frosty Morning', now in the Victoria and Albert Museum. [46] The largest known surviving trees in England are at East Coker, Somerset (30 m high, 95 cm d.b.h.), Termitts Farm near Hatfield Peverel, Essex (25 m high, 145 d.b.h.), and Melchbourne, Bedfordshire, (147 cm d.b.h.). [47]
The name Ulmus minor subsp. minor was used by R. H. Richens [48] for field elm that was not English elm, Cornish elm, Plot elm or Guernsey elm. Many publications, however, continue to use plain Ulmus minor for undifferentiated field elm; indeed Dr Max Coleman of Royal Botanic Garden Edinburgh argued in his 2002 paper 'British Elms' that there was no clear distinction between species and subspecies. [49] Some authorities, among them Richens [50] and Coleman, [13] include English elm among varieties of field elm, Richens calling English elm U. minor var. vulgaris. Richens sank as undifferentiated U. minor certain local English forms such as U. minor 'Goodyeri', U. minor 'Hunnybunii', U. minor 'Sowerbyi', and U. minor 'Coritana'.[ citation needed ]
Henry's Ulmus nitens var. italica, 'Mediterranean Elm' (1913), distinguished by its 14 to 18 pairs of leaf-veins, [51] was accepted, despite the wide source-area claimed for it ("Italy, Spain, Portugal and Algeria"), as U. carpinifolia var. italicaHenry, by Krüssman (1984), who included a photograph of a specimen in Gisselfeld Park, Denmark. [52] Bean (1988), however, considered it "a variety of rather dubious standing", [53] and it was ignored by Richens (1983).
U. canescens Melville and U. boissieri Grudz. were both sunk as U. minor by Richens. [54] The former is found throughout the eastern Mediterranean, including Palestine and Israel, and is distinguished by its leaves, densely downy on the underside when mature. [55] [56] The latter is a little-known tree found in Iran, in the Zagros forests and the Kerman / Kermanshah area. [57] Green and Richens also sank U. minor var. suberosa (Moench) Rehder - the so-called 'Cork-barked elm', korkulme (Germany) or wiąz korkowa (Poland), as a genetically random, maritime or juvenile form of U. minor, insufficiently differentiated to merit varietal status, its name a relic of taxonomic conservatism. [58] [59]
Numerous cultivars have been raised in Europe since the 18th century, although many are now probably either extinct owing to the ravages of Dutch elm disease, or survive unrecognized in sucker form:
The tree's natural range generously overlaps that of wych elm Ulmus glabra to the north, and readily hybridizes with it to produce the so-called 'Dutch elm' Ulmus × hollandica . [60]
In Spain and Italy Ulmus minor has naturally hybridized with Siberian elm U. pumila. In Spain U. pumila was introduced in the 16th century and has since spread widely, contributing to conservation concerns for U. minor. [61] In Italy U. pumila was introduced in the 1930s; research is ongoing into the extent of its hybridisation with U. minor. [62] The resulting hybrid has not yet been given a formal botanical name, though there are cultivated forms such as 'Recerta' and 'Fiorente' (see 'Hybrid cultivars').
U. minor hybridises naturally with U. glabra , producing elms of the Ulmus × hollandica group, from which there have arisen a number of cultivars:
The tree has featured strongly in artificial hybridization experiments in Europe and to a lesser extent in the United States. The hybrid Ulmus davidiana var. japonica × U. minor was raised at the Arnold Arboretum before 1924. [63] Most of the European research was based at Wageningen in the Netherlands until 1992, whence a number of hybrid cultivars have been commercially released since 1960. The earlier trees were raised in response to the initial Dutch elm disease pandemic that afflicted Europe after the First World War, and were to prove vulnerable to the much more virulent strain of the disease that arrived in the late 1960s. However, further research eventually produced several trees highly resistant to disease which were released after 1989. [64]
The elms by Willy Lott's Cottage and Flatford Mill, Suffolk, in Constable's paintings and drawings were, according to Richens, "smooth-leaved elm" (U. minor), [65] though the hedgerow elms in his Dedham Vale and East Bergholt landscape-paintings and drawings were otherwise "most probably East Anglian hybrid elms ... such as still grow in the same hedges". [66]
None known
Ulmus glabraHudson, the wych elm or Scots elm, has the widest range of the European elm species, from Ireland eastwards to the Ural Mountains, and from the Arctic Circle south to the mountains of the Peloponnese and Sicily, where the species reaches its southern limit in Europe; it is also found in Iran. A large deciduous tree, it is essentially a montane species, growing at elevations up to 1,500 m (4,900 ft), preferring sites with moist soils and high humidity. The tree can form pure forests in Scandinavia and occurs as far north as latitude 67°N at Beiarn in Norway. It has been successfully introduced as far north as Tromsø and Alta in northern Norway (70°N). It has also been successfully introduced to Narsarsuaq, near the southern tip of Greenland (61°N).
The field elm cultivar 'Atinia' , commonly known as the English elm, formerly common elm and horse may, and more lately the Atinian elm, was, before the spread of Dutch elm disease, the most common field elm in central southern England, though not native there, and one of the largest and fastest-growing deciduous trees in Europe. R. H. Richens noted that elm populations exist in north-west Spain and northern Portugal, and on the Mediterranean coast of France that "closely resemble the English elm" and appear to be "trees of long standing" in those regions rather than recent introductions. Augustine Henry had earlier noted that the supposed English elms planted extensively in the Royal Park at Aranjuez from the late 16th century onwards, specimens said to have been introduced from England by Philip II and "differing in no respects from the English elm in England", behaved as native trees in Spain. He suggested that the tree "may be a true native of Spain, indigenous in the alluvial plains of the great rivers, now almost completely deforested".
Ulmus minor subsp. minor, the narrow-leaved elm, was the name used by R. H. Richens (1983) for English field elms that were not English elm, Cornish elm, Lock elm or Guernsey elm. Many publications, however, continue to use plain Ulmus minor for Richens's subspecies, a name Richens reserved for the undifferentiated continental field elms. Dr Max Coleman of Royal Botanic Garden Edinburgh argued in his 2002 paper 'British Elms' that there was no clear distinction between species and subspecies.
Ulmus × hollandica 'Vegeta', sometimes known as the Huntingdon Elm, is an old English hybrid cultivar raised at Brampton, near Huntingdon, by nurserymen Wood & Ingram in 1746, allegedly from seed collected at nearby Hinchingbrooke Park. In Augustine Henry's day, in the later 19th century, the elms in Hinchingbrooke Park were U. nitens. Richens, noting that wych elm is rare in Huntingdonshire, normally flowering four to six weeks later than field elm, pointed out that unusually favourable circumstances would have had to coincide to produce such seed: "It is possible that, some time in the eighteenth century, the threefold requirements of synchronous flowering of the two species, a south-west wind", "and a mild spring permitting the ripening of the samaras, were met."
Ulmus laciniata(Trautv.) Mayr, known variously as the Manchurian, cut-leaf, or lobed elm, is a deciduous tree native to the humid ravine forests of Japan, Korea, northern China, eastern Siberia and Sakhalin, growing alongside Cercidiphyllum japonicum, Aesculus turbinata, and Pterocarya rhoifolia, at elevations of 700–2200 m, though sometimes lower in more northern latitudes, notably in Hokkaido.
The field elm cultivar Ulmus minor 'Stricta', known as Cornish elm, was commonly found in South West England, Brittany, and south-west Ireland, until the arrival of Dutch elm disease in the late 1960s. The origin of Cornish elm in the south-west of Britain remains a matter of contention. It is commonly assumed to have been introduced from Brittany. It is also considered possible that the tree may have survived the ice ages on lands to the south of Cornwall long since lost to the sea. Henry thought it "probably native in the south of Ireland". Dr Max Coleman of Royal Botanic Garden Edinburgh, arguing in his 2002 paper on British elms that there was no clear distinction between species and subspecies, suggested that known or suspected clones of Ulmus minor, once cultivated and named, should be treated as cultivars, preferred the designation U. minor 'Stricta' to Ulmus minor var. stricta. The DNA of 'Stricta' has been investigated and the cultivar is now known to be a clone.
The field elm cultivar Ulmus minor 'Plotii', commonly known as Lock elm or Lock's elm, Plot's elm or Plot elm, and first classified as Ulmus sativaMill. var. Lockii and later as Ulmus plotii by Druce in 1907-11, is endemic mainly to the East Midlands of England, notably around the River Witham in Lincolnshire, in the Trent Valley around Newark-on-Trent, and around the village of Laxton, Northamptonshire. Ronald Melville suggested that the tree's distribution may be related to river valley systems, in particular those of the Trent, Witham, Welland, and Nene. Two further populations existed in Gloucestershire. It has been described as Britain's rarest native elm, and recorded by The Wildlife Trust as a nationally scarce species.
The Field Elm cultivar Ulmus minor 'Sarniensis', known variously as Guernsey elm, Jersey elm, Wheatley elm, or Southampton elm, was first described by MacCulloch in 1815 from trees on Guernsey, and was planted in the Royal Horticultural Society's gardens in the 1820s. It was listed in the Loddiges catalogue of 1836 as Ulmus sarniensis and by Loudon in Hortus lignosus londinensis (1838) as U. campestris var. sarniensis. The origin of the tree remains obscure; Richens believed it "a mutant of a French population of Field elm", noting that "elms of similar leaf-form occur in Cotentin and in northern Brittany. They vary much in habit but some have a tendency to pyramidal growth. Whether the distinctive habit first developed on the mainland or in Guernsey is uncertain."
Ulmus × hollandica 'Major' is a distinctive cultivar that in England came to be known specifically as theDutch Elm, although all naturally occurring Field Elm Ulmus minor × Wych Elm U. glabra hybrids are loosely termed 'Dutch elm'. It is also known by the cultivar name 'Hollandica'. Nellie Bancroft considered 'Major' either an F2 hybrid or a backcrossing with one of its parents.
Ulmus × hollandicaMill. , often known simply as Dutch elm, is a natural hybrid between Wych elm and field elm Ulmus minor which commonly occurs across Europe wherever the ranges of the parent species overlap. In England, according to the field-studies of R. H. Richens, "The largest area [of hybridization] is a band extending across Essex from the Hertfordshire border to southern Suffolk. The next largest is in northern Bedfordshire and adjoining parts of Northamptonshire. Comparable zones occur in Picardy and Cotentin in northern France". Crosses between U. × hollandica and either of the parent species are also classified as U. × hollandica. Ulmus × hollandica hybrids, natural and artificial, have been widely planted elsewhere.
The hybrid elm cultivar Ulmus × hollandica 'Belgica', one of a number of hybrids arising from the crossing of Wych Elm with a variety of Field Elm, was reputedly raised in the nurseries of the Abbey of the Dunes, Veurne, in 1694. Popular throughout Belgium and the Netherlands in the 19th century both as an ornamental and as a shelter-belt tree, it was the 'Hollandse iep' in these countries, as distinct from the tree known as 'Dutch Elm' in Great Britain and Ireland since the 17th century: Ulmus × hollandica 'Major'. In Francophone Belgium it was known as orme gras de Malines.
Ulmus 'Exoniensis', the Exeter elm, was discovered near Exeter, England, in 1826, and propagated by the Ford & Please nursery in that city. Traditionally believed to be a cultivar of the Wych Elm U. glabra, its fastigiate shape when young, upward-curving tracery, small samarae and leaves, late leaf-flush and late leaf-fall, taken with its south-west England provenance, suggest a link with the Cornish Elm, which shares these characteristics. The seed, however, is on the stalk side of the samara, a feature of wych elm and its cultivars, whereas in hybrids it would be displaced towards the notch.
The elm cultivar Ulmus 'Hertfordensis Latifolia' was listed by Loudon in Arboretum et Fruticetum Britannicum (1838) as "the broad-leaved Hertfordshire Elm", and later mentioned, as Ulmus campestris hertfordensis latifolia, by Boulger in the Gardener's Chronicle, but without description. It was considered "probably U. carpinifolia" by Green, though broad leaves point to a possible Ulmus × hollandica hybrid identity. Hybrids of this type were once common in eastern Hertfordshire.
The 'dwarf' elm cultivar Ulmus 'Jacqueline Hillier' ('JH') is an elm of uncertain origin. It was cloned from a specimen found in a private garden in Selly Park, Birmingham, England, in 1966. The garden's owner told Hillier that it might have been introduced from outside the country by a relative. Hillier at first conjectured U. minor, as did Heybroek (2009). Identical-looking elm cultivars in Russia are labelled forms of Siberian Elm, Ulmus pumila, which is known to produce 'JH'-type long shoots. Melville considered 'JH' a hybrid cultivar from the 'Elegantissima' group of Ulmus × hollandica. Uncertainty about its parentage has led most nurserymen to list the tree simply as Ulmus 'Jacqueline Hillier'. 'JH' is not known to produce flowers and samarae, or root suckers.
The Field Elm cultivar Ulmus minor 'Coritana' was originally claimed by Melville, while he was searching in the neighbourhood of Leicestershire in 1936 for U. elegantissima, as a new species, which he called U. coritana. He later recorded its distribution in the counties of Bedfordshire, Berkshire, Buckinghamshire, Cambridgeshire, Essex, Hertfordshire, Leicestershire, Nottinghamshire, Norfolk, Oxfordshire, Suffolk and Warwickshire. Richens, however, dismissed U. coritana as 'an artificial aggregate' of local forms of Field Elm. Bean noted (1988) that Melville's U. coritana was not recognised in the Flora of the British Isles as a species distinct from U. carpinifolia [:U. minor].
The Field Elm cultivar Ulmus minor 'Suberosa', commonly known as the Cork-barked elm, is a slow-growing or dwarf form of conspicuously suberose Field Elm. Of disputed status, it is considered a distinct variety by some botanists, among them Henry (1913), Krüssmann (1984), and Bean (1988), and is sometimes cloned and planted as a cultivar. Henry said the tree "appears to be a common variety in the forests of central Europe", Bean noting that it "occurs in dry habitats". By the proposed rule that known or suspected clones of U. minor, once cultivated and named, should be treated as cultivars, the tree would be designated U. minor 'Suberosa'. The Späth nursery of Berlin distributed an U. campestris suberosa alataKirchn. [:'corky-winged'] from the 1890s to the 1930s.
The Field Elm cultivar Ulmus minor 'Viminalis Betulaefolia' (:'birch-leaved') is an elm tree of uncertain origin. An U. betulaefolia was listed by Loddiges of Hackney, London, in the catalogue of 1836, an U. campestris var. betulaefolia by Loudon in Arboretum et Fruticetum Britannicum (1838), and an U. betulifoliaBooth by the Lawson nursery of Edinburgh. Henry described an U. campestris var. betulaefolia at Kew in 1913, obtained from Fulham nurseryman Osborne in 1879, as "scarcely different from var. viminalis ". Melville considered the tree so named at Kew a form of his U. × viminalis, while Bean (1988), describing U. 'Betulaefolia', likewise placed it under U. 'Viminalis' as an apparently allied tree. Loudon and Browne had noted that some forms of 'Viminalis' can be mistaken for a variety of birch. An U. campestris betulaefolia was distributed by Hesse's Nurseries, Weener, Germany, in the 1930s.
The field elm cultivar Ulmus minor 'Viminalis' (:'willow-like'), occasionally referred to as the twiggy field elm, was raised by Masters in 1817, and listed in 1831 as U. campestris viminalis, without description. Loudon added a general description in 1838, and the Cambridge University Herbarium acquired a leaf specimen of the tree in 1866. Moss, writing in 1912, said that the Ulmus campestris viminalis from Cambridge University Herbarium was the only elm he thought agreed with the original Plot's elm as illustrated by Dr. Plot in 1677 from specimens growing in an avenue and coppice at Hanwell near Banbury. Elwes and Henry (1913) also considered Loudon's Ulmus campestris viminalis to be Dr Plot's elm. Its 19th-century name, U. campestris var. viminalis, led the cultivar to be classified for a time as a variety of English Elm. On the Continent, 'Viminalis' was the Ulmus antarcticaHort., 'zierliche Ulme' [:'dainty elm'] of Kirchner's Arboretum Muscaviense (1864).
The hybrid elm cultivar Ulmus × hollandica 'Viminalis' [:osier-leaved] was listed by the Späth nursery of Berlin as Ulmus scabraMill. var. viminalis in 1890 and as Ulmus montana viminalis from 1892. Though Späth's catalogues stated that it was "also distributed under the name planera aquatica", it remained in his lists under 'elm' and was accessioned by the Dominion Arboretum, Ottawa, and by the Royal Botanic Garden Edinburgh as an elm cultivar. A similar misidentification occurred in the mid-20th century, when the Siberian elm cultivar Ulmus pumila 'Poort Bulten' was for many years commercially propagated under the name Planera aquatica or 'water elm'. As the leaves of osier or Salix viminalis, however, differ markedly from those of Planera aquatica, being long, thin and tapering at both ends, Spath's name 'Viminalis' for this elm cultivar confirms that its leaves were not Planera-like. The probable explanation for the early distribution name is that Planera was the old name for Zelkova, a close relative of elm with willow-like leaves. It is therefore unlikely that 'Viminalis' was related in any way to the 19th-century elm cultivar Ulmus 'Planeroides'.
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