Ulmus glabra Huds., Wych Elm

Account Summary

Growth form and preferred habitats

A tall tree, more or less orbicular in outline, of lowland woods and hedges, most frequent in limestone areas where in the past it sometimes became dominant. It often occurs around lakes and along rivers and streams, but also grows below cliffs and occasionally in quarries.

Identification

Wych Elm has leaves which on their upper surface are very harsh in texture because of the presence of minute, dense, bristly hairs. The specific epithet 'glabra' does not refer to the leaves but to the bark on the twigs, which remains smooth for many years once it loses its initial downy pubescence (Hadfield 1957). The leaf base is one of the most distinctive vegetative identification features, it being very strongly asymmetric so that the ear-like lobe on the longer side actually conceals the short (2-5 mm) hairy leaf stalk or petiole. Before the devastation of Dutch elm disease killed mature Wych Elm trees, they alone of all elms seeded themselves abundantly every two or three years, the papery circular winged fruits being efficiently and widely dispersed by wind. U. glabra also differs from other elm species in failing to sucker, and these characters taken together enable it to be easily enough distinguished from the other forms of elm which are very much more critical and difficult to distinguish. The woodland historian Rackham (1980) reckoned that elms are the most difficult critical genus in the British flora.

Variation

Stace (2010) mentions that two 'ill-marked' regional subspecies are sometimes recognised: subsp. glabra, with broadly obovate leaves, more southern in distribution, and subsp. montana Hyl., with narrowly obovate leaves, a form that is more typical of the N & W of Britain and Ireland.

Native or introduced status

From the 18th century onwards, U. glabra was frequently planted along with oak and ash in woods on limestone in Fermanagh, as was common elsewhere in Ireland (McCracken 1971). However, while it is undoubtedly native in some of its more remote and inaccessible upland sites in the county, other trees must be self-sown from introduced planted stock, with the result that it is no longer feasible to distinguish between the two modes of origin.

Fermanagh occurrence

Whatever its origin, the tree was undoubtedly very frequent and widespread in Fermanagh until about 1990. It was recorded in both woods and hedges, most frequently in limestone areas of the county, often around lakes and along rivers and streams, but also in woods below cliffs and in quarries. It has been recorded in 127 tetrads, representing 24.1% of those in the VC, and 121 of them contained post-1975 records. There are just twelve post-2000 records in the Fermanagh Flora Database. The tree was very widespread in lowland Fermanagh, especially about Upper and Lower Lough Erne, but mature trees became increasingly rare from about 1995 onwards. The fate of these trees can only be reckoned a most dreadful pity, since U. glabra is the only undisputed native elm in Britain and Ireland (Mitchell 1996). While it never had the same dominance in our landscape when compared with the situation in S England, Wych Elm was still a significant and often very beautiful tree. In the Irish 8th century 'Laws of Neighbourhood' coding, it was given a strong level of protection in the second rank of the woody plant usefulness hierarchy, being regarded as, "a commoner of the wood" (Nelson & Walsh 1993).

Apart from the very rare isolated trees on remote rocky hillsides or lake shores, all the older specimens of Wych Elm previously recorded in our survey area have now died off from the virulent form of Dutch Elm disease which hit Fermanagh from the early- to mid-1980s onwards. While many younger Wych elms continue to die, others seem to be surviving and avoiding the attentions of the bark-boring beetle that is the vector carrying the fungal pathogen from tree-to-tree. Younger trees do not possess a sufficiently thick layer of bark to interest and attract the beetle, and thus for a time they avoid infection.

Dutch Elm disease

At the very end of the 19^th century, elm trees in Europe were first noticed to be inexplicably dying. The timing of the tree deaths around The Great War, and the way apparently healthy trees would suddenly up and die in midsummer, led many to assume that the deaths were related to nerve gas used by military combatants. Research led to the discovery of a fungal pathogen, and the ailment was named Dutch Elm disease because the species involved was first isolated and described by a young researcher in the Netherlands in 1921. When an elm becomes infected with the fungus, mycelial threads invade the water conducting tissues and eventually block them with fungal by-products (ie gums, plus irregular shaped growths of callus tissue (called 'tyloses'), and gas bubbles which break the water columns). When its xylem conducting tissues are completely blocked, the tree wilts and eventually it dies a slow death. Essentially the tree dies of drought, although fungal toxins, including a type called 'cerato-ulmin', also play a limited but significant part in its demise (Hadfield 1957; Ingram & Robertson 1999, p. 136).

An earlier attack of took place in Ireland during the 1930s (in Britain from 1927 onwards). In that outbreak, the affected trees often survived the attack, although the fungal infection did spread around the world producing a 'pandemic' disease epidemic affecting elms.

Fossil record – the elm fall

In vegetation history, the famous (or infamous) so-called 'elm fall' or 'elm decline' described how the fossil representation of Ulmus pollen grains preserved in peat and lake sediments in Britain, Ireland and indeed over the whole of NW Europe, suddenly dropped – not quite like a stone – around about 5200 years BP. The elm pollen decline was characterised by its abrupt and almost simultaneous occurrence across a wide area of western Europe (Smith & Pilcher 1973). The cause of the massive decline in the elm tree population, which these pollen records indicated, presented a major mystery to science 50 years ago when I was an undergraduate student.

While all research into prehistory inevitably views such distant vegetation changes through a glass darkly, modern dating methods have tightened up the focus, revising and sharpening the date of the elm population decline and giving us some idea of the duration of the process. A study by Sylvia Peglar in Norfolk places the classic major 'elm decline' at about 5000 BP. The fossil pollen record at Peglar's site demonstrates that the impact on the tree population did not produce a sudden, isolated population fall, but rather it happened over a period of six to seven years (Peglar & Birks 1993). Danish and Swedish workers have put the date of the same phase of elm decline in their areas of NW Europe occurring between 5790 and 5745 BP, and they suggest that it took place over a period of about 40 years. Additional, more detailed work carried out in Denmark, identified four periods of elm decline at dates of 6530, 6130, 5870 and 5410 BP, with 5870 BP identified as the 'classic' phase of elm decline. In NE Ireland, a study at Sluggan bog has also shown four phases of elm decline occurring after 5050 BP, the classic decline occurring at 4900 BP (Smith & Goddard 1991).

It now appears clear (although more work will need to be done before the following hypothesis is completely proven), that the most likely cause for the sudden and widespread loss of the elm pollen (indicating the death of mature trees) was not so much the arrival of Neolithic farmers clearing the land of forest to make fields (although this was definitely happening and obviously it did not help matters), nor a change of climate (ie it was towards the end of the 'Atlantic' period) but, rather, the trigger was a bout of fungal infection, similar in effect to the latest phase of 'Dutch Elm disease' that infected and killed elms throughout Britain and Ireland in the 1970s, specifically attacking the genus Ulmus (Molloy & O'Connell 1987; Peglar & Birks 1993; Mitchell 1995; Ingram & Robertson 1999; Pilcher & Hall 2001, pp. 33-35; Hall 2011).

Peglar & Birks (1993) make the perfectly feasible suggestion that perhaps human disturbance prior to the elm fall weakened and damaged the elm trees, so that they became more susceptible to attack by the disease-causing organism. They have provided circumstantial evidence in the form of pollen and charcoal data to support this idea. The discovery in Europe of fossil elm timber of mid-Holocene age containing characteristic elm bark beetle galleries, and more importantly, the discovery at a site in London (on Hampstead Heath of all places!), of wing cases of two individual beetles of the species (Scolytus scolytus (F.)), has proved for the first time that the insect carrier of Dutch elm disease was present in England prior to the time of the elm fall (Girling & Greig 1985; Parker et al. 2002).

Apart from the similar pattern of sudden and nearly synchronous elm disappearance across Britain and Ireland observed recently and in the fossil pollen record, circumstantial support for the hypothesis that disease was the main cause of the elm decline in the mid-Holocene comes from a fossil study by Peglar and Birks (1993) based in SE England, which found that Corylus avellana (Hazel), and to a lesser extent Taxus baccata (Yew), expanded after the pre-historic elm fall, just as hazel has done in the 1970s and 1980s in British woodlands where Wych Elm declined as a result of the modern Dutch elm disease epidemic (Rackham 1980).

Irish occurrence

Prior to the most recent fungal endemic in the 1960s and early 1970s, U. glabra was very common in N & E Ireland, although as already mentioned, it was not always indigenous. However, at the same time Wych Elm was scarce to absent in the wetter, more peaty soils of the west and far south of Ireland.

British occurrence

In Great Britain, likewise, U. glabra was ubiquitous throughout England, Wales and most of lowland Scotland, but now most mature trees in British and Ireland have been killed, except perhaps in Scotland (C.A. Stace, in: Preston et al. 2002).

European occurrence

The native European distribution shown by Jalas & Suominen (1976, Map 311), showed U. glabra widespread over W & C Europe from the British Isles eastwards to the Urals, while in the north it reaches 60N in Russia, and 67N up the coast of Norway. In SE Europe, the distribution also reaches Turkey, and stretches eastwards to the Caucasus Mountains and N Iran (Jonsell et al. 2000). Dutch Elm disease devastated the elm population of parts of Denmark and S Sweden in the late 20th century, and it eventually reached the Oslo area of Norway in the 1990s.

Names

The genus name 'Ulmus' is the old Classical Latin name for the tree, very possibly derived from, or cognate with, the Celtic name 'ulm', and the Old Norse 'almr' (Johnson & Smith 1946; Grigson 1974). Grigson (1955, 1987) suggested that 'elm' was an Old English borrowing from the Latin 'ulmus', but in a very detailed linguistic thesis, Friedrich (1980, pp. 80-5), showed that the name 'elm' has a complicated ancestry in three stocks of Western Indo-European language: Italic, Celtic and Germanic. The Latin specific epithet 'glabra' means 'without hairs', or 'smooth' in this case (Gilbert-Carter 1964).

The English common name 'Wych Elm' bears no connotation of witches, but rather goes back to the Old English 'wice' and 'wic', meaning a tree with pliant or switchy bark, branches and timber, that could be used for weaving. Etymologists claim that elm names like 'wych' in English and 'vjaz' in Russian are closely linked to words meaning bending, binding and weaving (Heybroek 1993, p. 4-5; Friedrich 1980, p. 82-83). Elm tissues were thus used to weave ropes, baskets and other structures. The flexibility to be woven is also the case for some species of Sorbus, and most notably, numerous Salix trees and shrubs. Friedrich (1980) points out that Baltic and Slavic peasants and earlier tribal peoples of the same geographical area, used elm bast for making mats and footwear, customs that he speculates might go back to Proto-Indo-European prehistoric times. Nordhagen (1954) mentions German references to elm-bast being used for weaving second-rate (ie rough) textiles. Grigson (1987) lists eight associated or variant names that refer to these uses, including 'Quicken', 'Switch Elm' and 'Witan Elm'.

Uses

In the distant past, elm was used in many ways other than for timber, knowledge of which has almost completely died out in this part of the world. Across Europe for instance, Neolithic farmers cut elm branches and used the dried foliage and twigs as winter fodder (Nordhagen 1954; Heybroek 1963 & 1993). The latter Dutch author also lists other functional uses of the elm, eg as fodder for pigs, or as chopped and soaked bark fed to calves. Elm bark was even used as famine food by humans. Elm, closely followed by ash, was widely regarded as providing the best fodder of all for stock in winter, the branches being lopped, dried and stored, often by being stuck into the forks of the tree. A farmers' proverb from W Norway sums up the situation as, "Rowan nourishes, Elm fattens" (Troels-Smith 1960; Heybroek 1963). Scientific analysis confirms that dried elm leaves have a "starch equivalent" nutritive index of 50 to 64, while the comparable figures for good to very good meadow hay are only 48 to 57 (Heybroek 1963, p. 6).

Apart from the ancient and important historic uses already mentioned, most of which have long since been discontinued, mature Wych Elm gave (sadly past tense), excellent, beautiful, durable timber, suitable for the manufacture of furniture (especially chairs), and even for external windowsills of buildings. It was also the preferred timber for threshing floors, for the shafts of carts. Since it was suitably flexible, elm was also used for bow making - although in England it was secondary to imported yew for this particular arms manufacture (Grigson 1987).

The Danish archaeologist, Rolf Nordhagen has described how ancient people in Scandinavian countries and in N Russia, when cereals were in short supply made a flour substitute, scraped, pounded, sieved and carefully prepared from the inner bark of several tree species, of which Wych elm was the very much preferred "bread-tree". This practice was regularly revived right up into the twentieth century whenever disaster struck the cereal harvest. Nordhagen reports talking to old Norwegians who remembered bread wholly or partially baked with elm flour, or porridge made from it. The bark was stripped from young stems, not more than two or three years old, for this purpose (Nordhagen 1954, p. 301-303).

It has been found that harvesting branches and young shoots of elm at intervals of less than six years completely prevents the tree from flowering, so that prehistoric human activity could depress the pollen output, and hence modify the regional fossil pollen record. It is obvious that extensive reliance on elm branches and bark would immediately affect the reproductive and ecological success of the local tree population, and if the trees were regularly used, or excessively harvested from even once, this would seriously affect their survival, and in the longer term it could disrupt the species distribution. Nordhagen instances exactly this happening to U. glabra in some districts of E, W and N Norway. Fear of this outcome resulted in a cultural taboo developing against the felling or over-exploitation of Wych Elm in some parts of Norway, and to compensate for such pressure, elms were often planted near houses and they became venerated as an important bread reserve (Nordhagen 1954, p. 303).

At the same time there is strong support amongst palynologists for the belief that mid-Holocene human populations were too small to alone give rise to the nearly synchronous, sudden elm decline across Britain, which the fossil record demonstrates.

The medicinal use of elm was found by Allen and Hatfield (2004) to be an almost exclusively Irish phenomenon. The commonest use was of the slimy inner bark as a salve for burns and scalds. This muscilage was also used for skin problems in general, and more specifically, to treat swellings and sprains. The leaves were sometimes employed instead of the bark for swellings and inflammation. Other recorded uses in Ireland included to staunch bleeding, to cure jaundice, and to counteract ulcers, cancer and other "evils". In England, by comparison there were only two folk medicinal uses of elm; a tea brewed from the wood taken for eczema in Hampshire, and the inner bark crewed raw or made into a jelly and used for colds and sore throats by villagers in Wiltshire. The only veterinary use mentioned in folklore was for the expulsion of afterbirth in cows, and came from the NE of England and Scottish borders (Johnston 1853; Allen & Hatfield 2004, p. 358).

Threats

Dutch Elm disease has destroyed almost all the older trees of this species in Ireland, as it has done everywhere in England and Wales. However, there is a degree of resistance within the species, and young trees with bark unsuitable for the beetle do escape infection, at least for a time.

• Find out more about the format of the species accounts
• View abbreviations
• View references for all species accounts
• View a gazetteer of all the sites