Ulmus rubra

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Ulmus rubra
Mature Ulmus rubra in graveyard.jpg
Mature cultivated slippery elm (Ulmus rubra)
Scientific classification edit
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Clade: Rosids
Order: Rosales
Family: Ulmaceae
Genus: Ulmus
Subgenus: U. subg. Ulmus
Section: U. sect. Ulmus
U. rubra
Binomial name
Ulmus rubra
Ulmus rubra range map 3.png
Natural range of Ulmus rubra
  • 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

Ulmus rubra, the slippery elm, is a species of elm native to eastern North America. Other common names include red elm, gray elm, soft elm, moose elm, and Indian elm.


Ulmus rubra is a medium-sized deciduous tree with a spreading head of branches,[4] commonly growing to 12–19 metres (39–62 feet), very occasionally over 30 m (98 ft) in height. Its heartwood is reddish-brown. The broad oblong to obovate leaves are 10–20 centimetres (4–8 inches) long, rough above but velvety below, with coarse double-serrate margins, acuminate apices and oblique bases; the petioles are 6–12 millimetres (141532 in) long.[5] The leaves are often tinged red on emergence, turning dark green by summer and a dull yellow in autumn.[6] 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 (15322332 in) long, the single, central seed coated with red-brown hairs, naked elsewhere.[5]

Similar species[edit]

The species superficially resembles American elm (Ulmus 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 is chiefly distinguished from American elm by its downy twigs, chestnut brown or reddish hairy buds, and slimy red inner bark.


The tree was first named as part of Ulmus americana in 1753,[8] but identified as a separate species, U. rubra, in 1793 by Pennsylvania botanist Gotthilf Muhlenberg. The slightly later name U. fulva, published by French botanist André Michaux in 1803,[9] is still widely used in information related to dietary supplements and alternative medicine.


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

The reddish-brown heartwood lends the tree the common name 'red elm'.

Distribution and habitat[edit]

The species is 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.[10]


Pests and diseases[edit]

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][unreliable source?]


In the central United States, native U. rubra hybridizes in the wild with the Siberian elm (U. pumila),[13][14] which was introduced in the early 20th century and has spread widely since, prompting conservation concerns for the genetic integrity of the former species.[15]


The species has seldom been planted for ornament in its native country. It occasionally appeared in early 20th-century US nursery catalogues.[16] 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.[5] 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 (vide Wentworth Elm).[17] 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.[18] Several mature trees survive in Brighton (see Accessions). The tree was propagated and marketed in the UK by the Hillier & Sons nursery, Winchester, Hampshire, from 1945, with 20 sold in the period 1970 to 1976, when production ceased.[19][20]

U. rubra was introduced to Europe in 1830.[8]

There are no known cultivars, though Meehan misnamed Ulmus americana 'Beebe's Weeping' as U. fulva pendula (1889) and Späth misnamed Ulmus americana 'Pendula' U. fulva (Michx.) pendula Hort. (1890). The hybrid U. rubra × U. pumila cultivar 'Lincoln' is sometimes erroneously listed as U. rubra 'Lincoln'.

Hybrid cultivars[edit]

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'.[21] In later years, it was also used in the Wisconsin elm breeding program to produce 'Repura' and 'Revera'[22] 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).[23]


Cross-sections of moose elm from The American Woods


The mucilaginous inner bark of the tree is edible raw or boiled,[24] and was eaten by Native Americans. The bark can also be used to make tea.[25]


The species has various traditional medicinal uses. The inner bark 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 US Food and Drug Administration.[26] Sometimes the leaves are dried and ground into a powder, then made into a tea.


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,[27] 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.[28] The wood is also used for the hubs of wagon wheels, as it is very shock resistant owing to the interlocking grain.[29] 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.


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. Gaylord Perry wrote about how he used slippery elm tablets in his 1974 autobiography, Me and the Spitter.[30]


The tree's fibrous inner bark produces a strong and durable fiber that can be spun into thread, twine, or rope[29] useful for bowstrings, ropes, jewellery, clothing, snowshoe bindings, woven mats, and even some musical instruments.[citation needed] 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.[citation needed]


Notable trees[edit]

A tree in Westmount, Quebec, Canada, measured 4.27 m (14 ft) in girth in 2011.[31][32] The US national champion, measuring 7.16 m (23+12 ft) in circumference and 27.4 metres (90 ft) tall, with an average crown spread of 25.18 metres (82+12 ft) wide, grows in Kentucky.[33] Another tall specimen grows in the Bronx, New York City, at 710 West 246th Street, measuring 31 m (102 ft) high in 2002.[34] In the UK, there is no designated Tree Register champion.


North America[edit]




  1. ^ Stritch, L. (2018). "Ulmus rubra". IUCN Red List of Threatened Species. 2018: e.T61967382A61967384. doi:10.2305/IUCN.UK.2018-1.RLTS.T61967382A61967384.en. Retrieved 12 November 2021.
  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. ^ Hillier & Sons. (1990). Hillier's Manual of Trees & Shrubs, 5th ed.. David & Charles, Newton Abbot, UK
  5. ^ a b c Bean, W. J. (1970). Trees & Shrubs Hardy in the British Isles, 8th ed., p. 656. (2nd impression 1976) John Murray, London. ISBN 9780719517907
  6. ^ Missouri Botanical Garden, Ulmus rubra
  7. ^ a b c 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. ^ a b J., White; D., More (2003). Trees of Britain & Northern Europe. Cassell, London. ISBN 0-304-36192-5.
  9. ^ Michaux, A. (1803). Flora Boreali-Americana ("The Flora of North America")
  10. ^ 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). Vol. 2 – via Southern Research Station.
  11. ^ "Ulmus rubra". Illinois State Museum.
  12. ^ "Elm Leaf Beetle Survey". Archived from the original on 2011-07-19. Retrieved 17 July 2017.
  13. ^ 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. S2CID 7294817.
  14. ^ 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.
  15. ^ 'Conservation status of red elm (Ulmus rubra) in the north-central United States', elm2013.ipp.cnr.it/downloads/book_of_abstracts.pdf. Cached pp. 33–35
  16. ^ Frederick W. Kelsey, Descriptive catalogue, no. 55, N.Y., 1906
  17. ^ Accessions book. Royal Botanic Garden Edinburgh. 1902. pp. 45, 47.
  18. ^ "List of Living Accessions: Ulmus". Royal Botanic Garden Edinburgh. Retrieved 21 September 2016.
  19. ^ Hillier & Sons (1977). Catalogue of Trees & Shrubs. Hillier, Ampfield, UK.
  20. ^ Hillier & Sons Sales inventory 1962 to 1977 (unpublished).
  21. ^ Green, Peter Shaw (1964). "Registration of cultivar names in Ulmus". Arnoldia. Arnold Arboretum, Harvard University. 24 (6–8): 41–80. Retrieved 16 February 2017.
  22. ^ 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.
  23. ^ Brookes, Andrew (2020). "Disease resistant elm cultivars" (PDF). Hampshire & Isle of Wight Branch Butterfly Conservation.
  24. ^ 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.
  25. ^ Angier, Bradford (1974). Field Guide to Edible Wild Plants. Harrisburg, PA: Stackpole Books. p. 206. ISBN 0-8117-0616-8. OCLC 799792.
  26. ^ 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.

  27. ^ Macoun, J. M. (1900). The Forest Wealth of Canada, p. 24. Canadian Commission for the Paris International Exhibition 1900.
  28. ^ Pinchot, G. (1907). U S Forest Circular, no.85.
  29. ^ a b Werthner, William B. (1935). Some American Trees: An intimate study of native Ohio trees. New York: The Macmillan Company. pp. xviii + 398.
  30. ^ Anderson, Dave (August 9, 1973). "Gaylord Perry's Confession". The New York Times. Retrieved July 15, 2022.
  31. ^ Ulmus rubra, Cedar Crescent, Westmount, Quebec
  32. ^ 'L'Orme Rouge ou l'Indian Elm de la rue Cedar Crescent'
  33. ^ "Slippery Elm - KY". American Forests. Retrieved 2022-06-12.
  34. ^ Barnard, E. S. (2002) New York City Trees. New York: Columbia University Press. ISBN 0-231-12835-5
  35. ^ "List of plants in the {elm} collection". Brighton & Hove City Council. Retrieved 23 September 2016.

External links[edit]