''Ulmus mexicana'', the Mexican elm, is a large tree

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...

to Mexico and Central America. It is most commonly found in cloud forest and the higher elevations () of tropical rain forest with precipitation levels of per year,Moreira, I. & Arnaez, E. (2003) ''Ulmus mexicana'' (Liebm.) Planch., ''Tropical Tree Seed Manual'', 770–771, RNGR, USDA Forest Service, USA

/ref> ranging from San Luis Potosi south to

Chiapas Chiapas (; Tzotzil language, Tzotzil and Tzeltal language, Tzeltal: ''Chyapas'' ), officially the Free and Sovereign State of Chiapas ( es, Estado Libre y Soberano de Chiapas), is one of the states that make up the Political divisions of Mexico, ...

in Mexico, and from Guatemala to Panama beyond. The tree was first described botanically in 1873.

Description

''Ulmus mexicana'' is one of the tallest elm species, occasionally reaching a height of , and a

d.b.h. Diameter at breast height, or DBH, is a standard method of expressing the diameter of the trunk or bole of a standing tree. DBH is one of the most common dendrometric measurements. Tree trunks are measured at the height of an adult's breast, ...

of 2.5 m (8 feet), certainly one of the tallest trees in Mexico. The tree is also distinguished by its deeply fluted grey trunk, supporting a deep crown, its dense foliage casting a heavy shadow. The leaves vary widely in size from 3–16 cm in length by 2–7 cm breadth,

elliptic In mathematics, an ellipse is a plane curve surrounding two focal points, such that for all points on the curve, the sum of the two distances to the focal points is a constant. It generalizes a circle, which is the special type of ellipse in ...

obovate The following is a list of terms which are used to describe leaf morphology in the description and taxonomy of plants. Leaves may be simple (a single leaf blade or lamina) or compound (with several leaflets). The edge of the leaf may be regular o ...

, surface glossy, but dull on the underside, with petioles 5–10 mm long. The tree has distinctive racemose inflorescences up to 7 cm in length comprising nine clusters of 40 perfect

apetalous Petals are modified leaves that surround the reproductive parts of flowers. They are often brightly colored or unusually shaped to attract pollinators. All of the petals of a flower are collectively known as the ''corolla''. Petals are usually ...

wind-pollinated flowers which emerge between December and February. The small

samara Samara ( rus, Сама́ра, p=sɐˈmarə), known from 1935 to 1991 as Kuybyshev (; ), is the largest city and administrative centre of Samara Oblast. The city is located at the confluence of the Volga and the Samara (Volga), Samara rivers, with ...

e, 9.0 × 2.3 mm, are covered with long straight hairs, and are shed in March 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
Natural regeneration is poor.

Uses

Although much of its natural range is threatened by deforestation, the tree is singularly unpopular in the timber trade on account of its deeply fluted trunk, and thus not considered endangered. The timber is hard and heavy (Gs 0.55), but difficult to dry, and can warp badly. Moreover, its high silica content (0.35) damages tools. The wood is used for tools, furniture, and floors, whilst the foliage is commonly used as fodder for cattle. The tree is occasionally planted for shade or ornamentation.

Etymology

In Costa Rica the Mexican elm is known as ''Tirrá''; the neighbourhood (district) of Tirrases in

Curridabat Curridabat is a district of the Curridabat canton, in the San José province of Costa Rica. Geography Curridabat has an area of km2 and an elevation of metres. It is situated on the eastern border of the San José capital city, north of ...

, San José, takes its name from the tree.

References

External links

*https://web.archive.org/web/20060627090133/http://cloudbridge.org/trees/ulmus_mexicana.html The Mexican Elm in Costa Rica * {{Taxonbar, from=Q430029 mexicana Elm species and varieties Flora of Central America Flora of Costa Rica Flora of Guatemala Flora of Panama Trees of Central America Trees of Mexico Trees of Costa Rica Trees of Guatemala Trees of Panama Trees of San Luis Potosí Plants described in 1873 Ulmus articles missing images Cloud forest flora of Mexico Flora of the Central American montane forests Flora of the Sierra Madre Oriental Flora of the Sierra Madre de Oaxaca Flora of the Sierra Madre del Sur