|Natural range (Florida population excluded)|
Ulmus crassifolia Nutt., the Texas cedar elm or simply cedar elm, is a deciduous tree native to south central North America, mainly in southern and eastern Texas, eastern Oklahoma, Arkansas and Louisiana, with small populations in western Mississippi, southwest Tennessee and northwestern Florida; it also occurs in northeastern Mexico. The tree typically grows well in flat valley bottom areas referred to as 'Cedar Elm Flats'. The common name 'cedar elm' is derived from the trees' association with juniper trees, locally known as cedars.
The cedar elm is a medium-sized to large deciduous tree growing to 24 – 27 m tall with a rounded crown. The leaves are small, 2.5 – 5 cm long by 1.3 – 2 cm broad, with an oblique base, and distinguish it from Ulmus serotina with which it readily hybridizes in the wild. Leaf fall is late in the year, often in early winter. The wind-pollinated apetalous perfect flowers are produced in the late summer or early fall; they are small and inconspicuous, with a reddish-purple color. The fruit is a small winged samara 8 – 10 mm long, maturing quickly after the flowering in late fall.
Pests and diseases
Cedar elm is susceptible to Dutch elm disease (DED), though less so than American elm, and moderately damaged by the elm leaf beetle Xanthogaleruca luteola. The tree also suffers from a vascular wilt, the symptoms often confused with those of DED, whilst in Texas it is damaged by Spanish moss Tillandsia usneoides, which drapes across the branches weakening the tree, occasionally killing it.
Cedar elms are very susceptible to mistletoe. Mistletoe is a parasite that roots itself in to the vascular system of the tree, thus stealing valuable nutrients and water. In some cases, if not removed the parasite can be devastating to large sections of trees and even fatal. They create club like branches that die out at the ends. These "club" branches create openings for future pests like the elm beetles and carpenter ants. There are no known treatments that are safe enough to kill mistletoe without killing the tree. Removing the mistletoe manually is not a guarantee, however it is the best known method for control.
- Arnold Arboretum. Acc. nos. 511-2002, 758-86, both wild collected.
- Chicago Botanic Garden, Glencoe, Illinois. No details available.
- Bartlett Tree Experts. Acc. no. 90-1243, unrecorded provenance.
- Morton Arboretum. Acc. no. 385-68*1.
- New York Botanical Garden. Acc. no. 79617, unrecorded provenance.
- U S National Arboretum, Washington, D.C., USA. Acc. no. 37834
- Grange Farm Arboretum, Sutton St. James, Spalding, Lincolnshire, UK. Acc. no. 509
- Royal Botanic Garden Edinburgh. Acc. no. 20080090, from seed wild collected in USA.
- Sir Harold Hillier Gardens, UK. Acc. no. 1980-0443, (Brentry Field).
- University of Copenhagen Botanic Garden. No details available.
- "Map: Ulmus crassifolia". Efloras.org. Retrieved 2013-09-01.
- Todzia, C. A. & Panero, J. L. (2006). A new species of Ulmus (Ulmaceae) from southern Mexico and a synopsis of the species in Mexico. Brittonia, Vol 50, (3): 346
- "A New Species of Ulmus (Ulmaceae) from Southern Mexico and a Synopsis of the Species in Mexico". Jstor.org. Retrieved 2013-11-30.
- "Ulmus crassifolia in Flora of North America @". Efloras.org. Retrieved 2013-09-01.
- "Plants Profile for Ulmus crassifolia (cedar elm)". Plants.usda.gov. Retrieved 2013-09-01.
- "Ulmus crassifolia Nutt". Na.fs.fed.us. Retrieved 2013-09-01.
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- Elwes, H. J. & Henry, A. (1913). The Trees of Great Britain & Ireland. Vol. VII. 1848–1929. Republished 2004 Cambridge University Press, ISBN 9781108069380
- Auckland Botanical Society (2003). Journal Vol. 58 (1), June 2003. ISSN 0113-41332
- American Forests. (2012). The 2012 National Register of Big Trees.
- "''Ulmus crassifolia'' at Morton Arboretum". Cirrusimage.com. 2010-05-06. Retrieved 2013-09-14.
- Ramon Jordan. "US National Arboretum :". Usna.usda.gov. Retrieved 2013-09-01.
- "English". Arboretum-waasland.be. Retrieved 2013-09-01.