Ulmus rubra

Ulmus rubra, the slippery elm, is a species of elm native to eastern North America, ranging from southeast North Dakota, east to Maine and southern Quebec, south to northernmost Florida, and west to eastern Texas, where it thrives in moist uplands, although it will also grow in dry, intermediate soils.[4] Other common names include red elm, gray elm, soft elm, moose elm, and Indian elm. The tree was first named as part of Ulmus americana in 1753,[5] but identified as a separate species, Ulmus rubra, in 1793 by Pennsylvania botanist Gotthilf Muhlenberg. The slightly later name U. fulva, published by French botanist André Michaux in 1803,[6] is still widely used in dietary-supplement and alternative-medicine information.

"Red Elm" redirects here. For the community in the United States, see Red Elm, South Dakota.

Ulmus rubra
Mature cultivated slippery elm (Ulmus rubra)

Least Concern  (IUCN 3.1)[1]
Scientific classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Clade: Rosids
Order: Rosales
Family: Ulmaceae
Genus: Ulmus
Subgenus: U. subg. Ulmus
Section: U. sect. Ulmus
Species:
U. rubra
Binomial name
Ulmus rubra
Natural range of Ulmus rubra
Synonyms
  • Ulmus americana L. var. rubra Aiton
  • Ulmus crispa Willd.
  • Ulmus dimidiata Raf.
  • Ulmus elliptica Anon.[3]
  • Ulmus fulva Michx., Loudon, Bentley & Trimen, Sarg.
  • Ulmus Heyderi Späth
  • Ulmus pinguis Raf.
  • Ulmus pubescens Walter

The species superficially resembles American elm (U. americana), but is more closely related to the European wych elm (U. glabra), which has a very similar flower structure, though lacks the pubescence over the seed.[7] U. rubra was introduced to Europe in 1830.[5]

Description

Ulmus rubra is a medium-sized deciduous tree with a spreading head of branches,[8] commonly growing to 12–19 m (39–62 ft), very occasionally > 30 m (98 ft) in height. Its heartwood is reddish-brown, giving the tree its alternative common name 'red elm'. The species is chiefly distinguished from American elm by its downy twigs, chestnut brown or reddish hairy buds, and slimy red inner bark. The broad oblong to obovate leaves are 10–20 cm (4–8 in) long, rough above but velvety below, with coarse double-serrate margins, acuminate apices and oblique bases; the petioles are 6–12 mm (1⁄4–15⁄32 in) long.[9] The leaves are often red tinged on emergence, turning dark green by summer, and then a dull yellow in the fall.[10] The perfect, apetalous, wind-pollinated flowers are produced before the leaves in early spring, usually in tight, short-stalked, clusters of 10–20. The reddish-brown fruit is an oval winged samara, orbicular to obovate, slightly notched at the top, 12–18 mm (15⁄32–23⁄32 in) long, the single, central seed coated with red-brown hairs, naked elsewhere.[9]

  • Downy leaf bud and flower buds of U. rubra
  • U. rubra flowers
  • Asymmetrical leaf of Ulmus rubra
  • Mature trunk bark
  • Slippery elm, Chippewa National Forest, Minnesota, 1923
  • Downy leaf-buds and seed area of samarae

Pests and diseases

The tree is reputedly less susceptible to Dutch elm disease than other species of American elms,[11] but is severely damaged by the elm leaf beetle (Xanthogaleruca luteola).[12]

  • Red elm bark browsed by horses, Marshall, Illinois

Cultivation

The species has seldom been planted for ornament in its native country. It occasionally appeared in early 20th-century US nursery catalogues.[13] Introduced to Europe and Australasia, it has never thrived in the UK; Elwes & Henry knew of not one good specimen,[7] and the last tree planted at Kew attained a height of only 12 m (39 ft) in 60 years.[9] Specimens supplied by the Späth nursery to the Royal Botanic Garden Edinburgh in 1902 as U. fulva may survive in Edinburgh as it was the practice of the Garden to distribute trees about the city (viz. the Wentworth Elm).[14] A specimen at RBGE was felled c.1990. The current list of Living Accessions held in the Garden per se does not list the plant.[15] Several mature trees survive in Brighton (see Accessions).

Notable trees

A tree in Westmount, Quebec, Canada, measured 4.27 m in girth in 2011.[16][17] The US National Champion, measuring 7.16 m in circumference and 27.4 m tall, with an average crown spread of 25.18 m wide, grows in Louisville, Kentucky.[18][19] Another tall specimen grows in the Bronx, New York City, at 710 West 246th Street, measuring 31 m (102 ft) high in 2002.[20] In the UK, there is no designated TROBI champion.

Cultivars

There are no known cultivars. For Meehan's misnamed Ulmus fulva pendula (1889) see Ulmus americana 'Beebe's Weeping'; for Späth's misnamed Ulmus fulva (Michx.) pendula Hort. (1890) see Ulmus americana 'Pendula'. The hybrid U. rubra × U. pumila cultivar 'Lincoln' is occasionally listed as Ulmus rubra 'Lincoln' in error.

Hybrids

In the central United States, native U. rubra hybridizes in the wild with the Siberian elm (U. pumila),[21][22] which was introduced in the early 20th century and has spread widely since, prompting conservation concerns for the genetic integrity of the former species.[23]

Hybrid cultivars

U. rubra had limited success as a hybrid parent in the 1960s, resulting in the cultivars 'Coolshade', 'Fremont', 'Improved Coolshade', 'Lincoln', 'Rosehill', and probably 'Willis'.[24] In later years, it was also used in the Wisconsin elm breeding program to produce 'Repura' and 'Revera' [25] although neither is known to have been released to commerce. In Germany, the tree formed part of a complex hybrid raised by the Eisele nursery in Darmstadt, provisionally named 'Eisele H1'; patent pending (2020). [26]

Etymology

The specific epithet rubra (red) alludes to the tree's reddish wood, whilst the common name "slippery elm" alludes to the mucilaginous inner bark.

Uses
Cross-sections of moose elm from The American Woods

Medicinal

Ulmus rubra has various traditional medicinal uses. The mucilaginous inner bark of the tree is edible[27] has long been used as a demulcent, and is still produced commercially for this purpose in the United States with approval for sale as an over-the-counter demulcent by the U.S. Food and Drug Administration.[28] Sometimes leaves are dried and ground into a powder, then made into a tea.

Timber

The timber is not of much importance commercially, and is not found anywhere in great quantity.[7] Macoun considered it more durable than that of the other elms,[29] and better suited for railway ties, fence-posts, and rails, while Pinchot recommended planting it in the Mississippi valley, as it grows fast in youth, and could be utilized for fence-posts when quite young, since the sapwood, if thoroughly dried, is quite as durable as the heartwood.[30] The wood is also used for the hubs of wagon wheels, as it is very shock resistant owing to the interlocking grain.[31] The wood, as 'red elm', is sometimes used to make bows for archery. The yoke of the Liberty Bell, a symbol of the independence of the United States, was made from slippery elm.

Baseball

Though now outmoded, slippery elm tablets were chewed by spitball pitchers to enhance the effectiveness of the saliva applied to make the pitched baseball curve.[32]

Miscellaneous

The tree's fibrous inner bark produces a strong and durable fiber that can be spun into thread, twine, or rope[31] useful for bowstrings, ropes, jewellery, clothing, snowshoe bindings, woven mats, and even some musical instruments. Once cured, the wood is also excellent for starting fires with the bow-drill method, as it grinds into a very fine flammable powder under friction.

Accessions
North America
Europe
Australasia

References
  1. Stritch, L. (15 February 2018). "Ulmus rubra". IUCN Red List of Threatened Species. 2018: e.T61967382A61967384. doi:10.2305/IUCN.UK.2018-1.RLTS.T61967382A61967384.en. Retrieved 19 November 2019.
  2. "Ulmus rubra". Germplasm Resources Information Network (GRIN). Agricultural Research Service (ARS), United States Department of Agriculture (USDA). Retrieved 2008-03-14.
  3. Plantago, Plant Index: Ulmus rubra
  4. Cooley, John H.; Van Sambeek, J. W. (1990). "Ulmus rubra". In Burns, Russell M.; Honkala, Barbara H. (eds.). Hardwoods. Silvics of North America. Washington, D.C.: United States Forest Service (USFS), United States Department of Agriculture (USDA). 2 – via Southern Research Station (www.srs.fs.fed.us).
  5. J., White; D., More (2003). "Trees of Britain & Northern Europe". Cassell, London. ISBN 0-304-36192-5.
  6. Michaux, A. (1803). Flora Boreali-Americana ("The Flora of North America")
  7. Elwes, H. J. & Henry, A. (1913). The Trees of Great Britain & Ireland. Vol. VII. 1862-4 (as U. fulva). Republished 2004 Cambridge University Press, ISBN 9781108069380
  8. Hillier & Sons. (1990). Hillier's Manual of Trees & Shrubs, 5th ed.. David & Charles, Newton Abbot, UK
  9. Bean, W. J. (1970). Trees & Shrubs Hardy in the British Isles, 8th ed., p. 656. (2nd impression 1976) John Murray, London. ISBN 9780719517907
  10. Missouri Botanical Garden, Ulmus rubra
  11. "Ulmus rubra". Illinois State Museum.
  12. "Elm Leaf Beetle Survey". Archived from the original on 2011-07-19. Retrieved 17 July 2017.
  13. Frederick W. Kelsey, Descriptive catalogue, no. 55, N.Y., 1906
  14. Accessions book. Royal Botanic Garden Edinburgh. 1902. pp. 45, 47.
  15. "List of Living Accessions: Ulmus". Royal Botanic Garden Edinburgh. Retrieved 21 September 2016.
  16. Ulmus rubra, Cedar Crescent, Westmount, Quebec
  17. 'L'Orme Rouge ou l'Indian Elm de la rue Cedar Crescent'
  18. American Forests - National Register of Champion Trees.
  20. Barnard, E. S. (2002) New York city trees. Columbia University Press, New York. ISBN 0-231-12835-5
  21. Zalapa, J. E.; Brunet, J.; Guries, R. P. (2008). "Isolation and characterization of microsatellite markers for red elm (Ulmus rubra Muhl.) and cross-species amplification with Siberian elm (Ulmus pumila L.)". Molecular Ecology Resources. 8 (1): 109–12. doi:10.1111/j.1471-8286.2007.01805.x. PMID 21585729.
  22. Elowsky, C. G., Jordon-Thaden, I. E., & Kaul, R. B. (2013). A morphological analysis of a hybrid swarm of native Ulmus rubra and introduced U. pumila (Ulmaceae) in southern Nebraska. Phytoneuron 2013-44: 1–23. ISSN 2153-733X.
  23. 'Conservation status of red elm (Ulmus rubra) in the north-central United States', elm2013.ipp.cnr.it/downloads/book_of_abstracts.pdf. Cached p.33-35
  24. Green, Peter Shaw (1964). "Registration of cultivar names in Ulmus". Arnoldia. Arnold Arboretum, Harvard University. 24 (6–8): 41–80. Retrieved 16 February 2017.
  25. Santamour, Frank S; Susan E Bentz (May 1995). "Updated checklist of elm (Ulmus) cultivars for use in North America". Journal of Arboriculture. 21 (3): 122–131.
  26. Brookes, Andrew (2020). "Disease resistant elm cultivars" (PDF). Hampshire & Isle of Wight Branch Butterfly Conservation.
  27. Little, Elbert L. (1980). The Audubon Society Field Guide to North American Trees: Eastern Region. New York: Knopf. p. 424. ISBN 0-394-50760-6.
  28. Braun, Lesley; Cohen, Marc (2006). Herbs and Natural Supplements: An Evidence-Based Guide (2nd ed.). Churchill Livingstone. p. 586. ISBN 978-0-7295-3796-4., quote:
    Although Slippery Elm has not been scientifically investigated, the FDA has approved it as a safe demulcent substance.
  29. Macoun, J. M. (1900). The Forest Wealth of Canada, p. 24. Canadian Commission for the Paris International Exhibition 1900.
  30. Pinchot, G. (1907). U S Forest Circular, no.85.
  31. Werthner, William B. (1935). Some American Trees: An intimate study of native Ohio trees. New York: The Macmillan Company. pp. xviii + 398.
  32. "Spitball - BR Bullpen". Baseball-Reference.com. Retrieved 28 May 2015.
  33. "List of plants in the {elm} collection". Brighton & Hove City Council. Retrieved 23 September 2016.
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