Appendices & Glossary - Botanical Research Institute of Texas

1340 APPENDIX TWENTY-ONE/COMMERCIALLY IMPORTANT TIMBER TREES OF EAST TEXAS
ULMUS AMERICANA L. AMERICAN ELM
(ULMACAEAE, ELM FAMILY)
Other Common Names: WHITE ELM, SOFT ELM, WATER ELM, GRAY ELM, COMMON ELM
Form and Size: medium to tall tree, 21–35(–40) m; trunk usually straight, to 1–3+ m in diameter, often soon branching, the
branches sharply rising (giving rise to a “vase” shape); crown broadly rounded, sometimes with a weeping appearance.
Leaves: deciduous, simple, alternate, the blades 7–12(–14) cm long, mostly 1.5–2 times as long as wide, rounded and asymmetrical
at base, apically tapering abruptly to a point, dark green, glabrous and smooth or slightly scabrous above,
paler and glabrous to densely soft-pubescent beneath, marginally usually doubly serrate; petiole ca. 5 mm, glabrous to
pubescent.
Buds: 4–6 mm long, broadest at the base and tapering to a sharp point, covered with tiny, reddish-brown, slightly hairy
scales.
Flowers: bisexual (perfect), in fascicles of 3–4 produced on long (1–2 cm), slender, drooping, pedicels; petals absent; calyx
slightly asymmetric, with 7–9 shallow lobes, the margins ciliate; stamens 7–9, the anthers red; pistil 1.
Fruits: in loose fascicles, drooping on elongate pedicels, dry, flattened, elliptic to ovate samaras ca. 1 cm long, the surfaces
glabrous but ciliate marginally.
Bark: thick, ash-gray to grayish-brown, with deep somewhat irregular and intersecting furrows that separate the broad
flat ridges/plates, the ridges composed of thin, closely pressed scales.
Wood: sapwood grayish white to light brown; heartwood thick, light brown to brown, frequently with a reddish tinge;
wood with grain typically interlocked; growth rings distinct.
Habitat: bottomlands, floodplains, terraces, deciduous woodlands, fencerows, generally in areas with significant moisture.
Range: widespread in Texas except for the extreme south and extreme northwest; widespread in the eastern U.S. and
southern Canada w to MT and TX.
Principal Uses: boxes, crates, paneling, flooring; because of its good bending qualities it is used for the arching or curved
parts of furniture; the interlocking grain makes it difficult to split (and thus useful for items like hockey sticks); because
of the decline of this species due to Dutch Elm Disease, AMERICAN ELM wood is of limited importance today.
Historical Uses: because of its strength, the wood was used for things susceptible to wear such as wagon wheel hubs, ship
decks, or mortars for grinding grain (by Native Americans). Other uses included slack cooperage (= barrels for storing
dry goods; it was considered one of the best woods for barrel staves, due to its excellent bending properties and resistance
to splitting), ship blocks, bark canoes (Native Americans), farm implements, construction and mining timbers, and
railroad ties.
Other Significant Information: AMERICAN ELMS are moderately fast growing and generally do not flower and fruit significantly
until they are 35–40 years old. This was once among the most popular ornamental trees in eastern North
America, and it was well known for its beautiful “vase” shape (expanding ± evenly from a narrow base to a full crown).
However, the wide spread of Dutch Elm Disease (thus named because it was discovered by scientists in the Netherlands)
has greatly impacted this species. The disease is caused by an ascomycete fungus, Ophiostoma ulmi (Buisman) Nannf.,
that was introduced into the U.S. on diseased logs from Europe (though the fungus is thought to have originated in
Asia). It was first discovered in North America in Colorado in the 1930s. This fungus, the spores of which are spread by
bark beetles or through tree to tree root grafts, blocks the vascular tissue, thus killing infected trees. The loss of every
tree on numerous elm-lined streets is a good lesson in the importance of planting a diversity of tree species (and avoiding
monocultures).
Recognition in the Field: alternate, simple, large (> 7 cm long) leaves that are asymmetrical at base, doubly toothed, and
have one main vein from the base; fruits small, flat, elliptic to ovate, winged, glabrous except for marginal cilia.