Ulmus glabra Huds.

Common names: olmo, olmo mayor, olmo de montaña, llamera; oma, om (catalan), llamagueiro (galician), zugarr, zumarr, ostozabala (basque).

Description

This elm achieves lower heights and thickness among the Iberian Ulmus species.

On the contrary, it has the longest leaves (< 18 cm), with pubescent petiole, a wide leaf blade with many secondary veins (12-19 pairs) and acute apex. It often shows in some blades one or several lateral prominent teeth, a diagnostic attribute for Ulmus glabra. The upper side is coarse and the back side glabrescent.

Flowers gather in round or globose bundles attached directly to the branchlets. They are typically bisexual, very small, consisting of an external, conic, membranaceous piece ended by 4-6 lobes; a male part with 4-8 stamens with exserted, prominent anthers and the female part made up of the pistil with a an obovate and compressed ovary and two divergent, whitish, very papillose stigmata.

Fruits also form attached clusters. Initially they are green, but in the full maturity turn to brownish-yellow. Its samaras are the longest (up to 25 mm), with glabrous edges and centered seed.

Biology and phenology

The profuse bloom is in early spring, some weeks before the leaves sprouting.

Fruits ripen in early spring (around April), shortly after leaves maturation followed by a quick dissemination as the first windy events occur (anemochory). Seeds show a very low longevity in natural conditions.

Distribution and ecology

In the Iberian Peninsula Ulmus glabra is spread from sea level (near the lighthouse of San Juan de Nieva, Asturias) to 1,800 m in Sierra Nevada. It occurs in riverbanks and close to watercourses and also in cliff bases or even in slope bases wherever the soil is wet enough to satisfy its development requirements. It is especially abundant in the Cantabrian Range, Northern Iberian Range and the Pyrenees, being also in Moncayo, Sierra de Guadarrama, Maestrazgo, Sierras de Alcaraz and Segura and Sierra Nevada.

This species requires highly humid soil during the whole vegetative period (it is hydrophile) and is less tolerant to summer high temperaturas that U. minor. It behaves as indifferent concerning the presence of soil carbonates.

Past uses

There are only few references about the use of its wood, but it is considered similar to Ulmus minor’s. Unlike other elm species, this one cannot sprout from roots.

Ulmus montana is other name for this taxon.

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