(Ulmus glabra) Wych elm

Ulmus glabra, the wych elm, Scotch elm or Scots elm, has the widest range of the European elm species, from Ireland eastwards to the Urals, and from the Arctic Circle south to the mountains of the Peloponnese in Greece; it is also found in Iran. A large, deciduous tree, it is essentially a montane species, growing at elevations of up to 1500 m, 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. Wych elm has also been successfully introduced to Narsarsuaq, near the southern tip of Greenland (61°N).

The tree was by far the most common elm in the north and west of the British Isles and is now acknowledged as the only indisputably British native elm species. Owing to its former abundance in Scotland, the tree is occasionally known as the Scotch or Scots elm; Loch Lomond said to be a corruption of the Gaelic Lac Leaman interpreted by some as 'Lake of the Elms', 'leaman' being the plural form of leam or lem, 'elm'.However, this is contested, the correct Gaelic name considered Loch Laomainn, its origin obscure.

Closely related species, such as Bergmann's elm U. bergmanniana and Manchurian elm U. laciniata, native to northeast Asia, were once sometimes included in Ulmus glabra;another close relative is the Himalayan or Kashmir elm U. wallichiana. Conversely, Ulmus ellipticaKoch from the Caucasus, considered a species by some authorities, is often listed as a regional form of U. glabra.

Classification
Subspecies
Some botanists, notably Lindquist (1931), have proposed two subspecies:

• Ulmus glabra subsp. glabra in the south of the species' range, with broad leaves, trees often with a short, forked trunk and a low, broad crown
• Ulmus glabra subsp. montana (Stokes) Lindqvist in the north of the species' range (northern Britain, Scandinavia), the leaves are narrower, trees commonly with a long single trunk and a tall, narrow crown.However, similar structures and leaves are found on wych elms in Italy, much further to the south.

There is much overlap between populations with these characters, and the distinction may be owing to environmental influence, rather than genetic variation; the subspecies are not accepted by Flora Europaea.

Description
The type sometimes reaches heights of 40 m, typically with a broad crown where open-grown, supported by a short bole < 2 m. d.b.h. There are not normally root suckers; natural reproduction is by seed alone. The tree is notable for its very tough, supple young shoots, which are always without the corky ridges or 'wings' characteristic of many elms. The alternate leaves are deciduous, 6–17 cm long by 3–12 cm broad, usually obovate with an asymmetric base, the lobe often completely covering the short (<5 mm) petiole; the upper surface is rough. Leaves on juvenile or shade-grown shoots sometimes have three or more lobes near the apex. The perfect hermaphrodite flowers appear before the leaves in early spring, produced in clusters of 10–20; they are 4 mm across on 10 mm long stems and, being wind-pollinated, are apetalous. The fruit is a winged samara 20 mm long and 15 mm broad, with a single, round, 6 mm seed in the centre, maturing in late spring.

Pests and diseases

While the species is highly susceptible to Dutch elm disease,it is less favoured as a host by the elm bark beetles which act as vectors. Research in Spain has indicated the presence of a triterpene, alnulin, rendering the tree bark less attractive to the beetle than the Field elm, though at 87 μg/g dried bark its concentration is not as effective as in Ulmus laevis (200 μg/g).Moreover, once the tree is dying, its bark is quickly colonized by the fungus Phoma, which radically reduces the amount of bark available for the beetle to breed on.In European trials, clones of apparently resistant trees were inoculated with the pathogen, causing 85 – 100% wilting, resulting in 68% mortality by the following year. DNA analysis by Cemagref (now Irstea) in France has determined the genetic diversity within the species is very limited, making the chances of a resistant tree evolving rather remote. 

The Swedish Forest Tree Breeding Association at Källstorp produced triploid and tetraploid forms of the tree, but these proved no more resistant to Dutch elm disease than the normal diploid form. 

In trials conducted in Italy, the tree was found to have a slight to moderate susceptibility to elm yellows, and a high susceptibility to the elm leaf beetle Xanthogaleruca luteola[6]. 

Cultivation
The wych elm is moderately shade-tolerant, but requires deep, rich soils as typically found along river valleys.However, the species is intolerant of flooding, as it is of prolonged drought.Although rarely used as a street tree owing to its shape, it can be surprisingly tolerant of urban air pollution, constricted growing conditions and severe pollarding.

As wych elm does not sucker from the roots, and any seedlings are often consumed by uncontrolled deer populations, regeneration is very restricted, limited to sprouts from the stumps of young trees. The resultant decline has been extreme, and the wych elm is now uncommon over much of its former range. It is best propagated from seed or by layering stooled stock plants, although softwood cuttings taken in early June will root fairly reliably under mist. 

Wych elm was widely planted in Edinburgh in the 19th century as a park and avenue tree, and despite losses it remains abundant there, regenerating through seedlings.It was introduced to New England in the 18th century, and to Australia in 1860. It was planted in the 19th century as U. montana at the Dominion Arboretum, Ottawa, Canadaand in Toronto.

Wood
Wych elm wood is prized by craftsmen for its colouring, its crazy grain, its 'partridge-breast' or 'catspaw' markings, and, when worked, its occasional iridescent greenish sheen or 'bloom'. The bosses on old trees produce the characteristic fissures and markings of 'burr elm' wood.Bosses fringed with shoots are burrs, whereas unfringed bosses are burls.

Notable trees
Perhaps the most famous wych elm avenue was The Long Walk, Windsor Great Park, planted in the 1670s on the instruction of John Evelyn and described by Elwes as "one of the finest and most imposing avenues in the world". The wych elms were felled in 1943.

E. M. Forster cites a particular wych elm, one that grew at his childhood home of Rooks Nest, Stevenage, Hertfordshire, sixteen times in his novel Howards End. This tree overhangs the house of the title and is said to have a "...girth that a dozen men could not have spanned..." Forster describes the tree as "...a comrade, bending over the house, strength and adventure in its roots." The wych elm of the novel had pigs' teeth embedded in the trunk by country people long ago and it was said that chewing some of the bark could cure toothache. In keeping with the novel's epigraph, "Only connect...", the wych elm may be seen by some as a symbol of the connection of humans to the earth. Margaret Schlegel, the novel's protagonist, fears that any "....westerly gale might blow the wych elm down and bring the end of all things..." The tree is changed to a chestnut in the 1991 film adaptation of Howards End.

The UK Champion listed in The Tree Register of the British Isles (TROBI) is at Brahan in the Scottish Highlands;it has a girth of 703 cm (2.23 m d.b.h.) and a height of 24 m. The oldest specimen in Edinburgh (2016) is believed to be the tree (girth 5.2 m) in the former grounds of Duddingston House, now Duddingston Golf Course.Other notable specimens in Edinburgh are to be found in Learmonth Gardens and The Meadows.

In Europe, a large tree planted 1620 grows at Bergemolo, 5 km south of Demonte in Piedmont, Italy (bole-girth 6.2 m, 2.0 m d.b.h., height 26 m., 2008).Other ancient specimens grow at Styria, in Austria, and at Grenzhammer, Germany (see Gallery). In 1998, over 700 healthy, mature trees were discovered on the upper slopes of Mount Šimonka in Slovakia, but it is now believed they had survived courtesy of their isolation from disease-carrying beetles rather than any innate resistance; 50 clones of these trees were presented to HRH The Prince of Wales for planting at his Highgrove Estate, and at Clapham, Yorkshire.
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