Is Celtis australis a native tree to the Mediterranean area?

Leaves of Celtis australis L., near Navajas (Castellón, Spain) © E. Laguna, 2007

Celtis australis –the European Hackberry- was choosen as one of the 8 species representative of the Mediterranean bassin eco-region, in order to develop the project FILMED. The election was made after the evidence of its distribution area, extended by all the areas with typical Mediterranean climate, mainly by the Western and Northern sides of the Mediterranean bassin.

Riverine forests of Celtis australis L. near Navajas (Castellón, Spain) © E. Laguna, 2007

However, after consultation with several expertises from other Mediterranean countries, we noticed that C. australis could be an archaeophyte introduced in Central and Western Mediterranean from the Himalayan mountains and the Irano-Turanian area in ancient times, in order to obtain their benefits (wood, fruits). C. australis is still used around the Mediteranean sea as the main provider of wood and branches to make agricultural tools. The hypothesis of a primitive introduction from Eastern territories can be tested by the FILMED protocoles, if seeds or plant material from the possible origin areas is received.

Is Celtis australis suffering graphiosis attacks?

In a recent excursion to the river Zarra (Western side of the province of Valencia), Drs. Rafael Currás and Emilio Laguna saw ill specimens of Celtis australis L., whose external aspect reminded the efects of the Graphiosis disease, caused by Ceratocystis ulmi on most species of the genus Ulmus -Elm Tree-. In the next months, the collaboration of several specialists will be requested to test the hypothesis of the Ceratocystis’ attacks, samplimg branches and leaves of the affected population.

Mixed forests of Populus sp. pl. and Celtis australis L., on the terraces bordering the river Zarra (Valencia, Spain) © E. Laguna 2007

The graphiosis have destroyed most part of the European populations of native species of Ulmus, and particularly on the best adapted species to Mediterranean conditions like Ulmus minor. Its extension to other species of Ulmaceae can signify a serious problem in terms of conservation, due that some species are threatened endemic plants (i.e. Zelkova sicula, endemic to Sicily). In the case of Celtis australis, the disease could put in peril the traditional handcrafting activity made with the branches of this species in several parts of the Mediterranean area, and its associated cultural landscapes.

Dangerous harvesting of Celtis samples in Valencia

A few days ago, Drs. R. Currás & E. Laguna had a disagreable surprise picking Celtis australis samples up in the 'theorically' dry river Zarra (Valencia, Spain). Unexpected summer rains converted the path crossing the river meadows into a trap to catch the FILMED's 4x4 car. After a couple of hours the car was definitively rescued, having enough time to harvest all the Celtis samples.

On the leaf size in Rhamnus alaternus

External aspect of Rhamnus alaternus in Les Planes, near the 'Cap of Sant Antoni', Xàbia, Alicante

One of the Filmed's species showing more morphological variability rates is Rhamnus alaternus L. In Mediterranean Spain, most populations use to be shrubs (up to 2-2,5 m tall) small-leaved, showing rigid, spiny, little leaves (2-3 cm long). However, the populations of the Thyrrenic and Central Mediterranean area often are big-leaved trees, using to overpass 4 cm in length. Some relictic populations found in the Valencian Community (Eastern Spain) are big-leaved (up to 6-7 cm in length) trees (up to 5-6 m tall), bearing brilliant, lauroid leaves, entire or slighty denticulated. The most important population have been found in the Nature Park 'El Montgó' (Dénia and Xàbia, NE of Alicante), in the so-called 'dianic' area, the Easternmost continental outcroop of the Betic mountains, sharing most of its plant checklist with the island of Eivissa/Ibiza -nowadays forming part of the Balearic archipelago, but belonging the Betic cordillera by the end of the Miocene-. These stunning plants only live in karstic soils of the 'Cap de Sant Antoni' and its surrounding plateau ('Les Planes de Xàbia'), and their external aspect is like the trees of the same species found in the calcareous grounds of Minorca (Balearic Islands). The molecular analyses developed by the project FILMED will clarify the relationships between the Montgo and the Balearic Islands for this species. Where was really born this species?.

Leaf of Rhamnus alaternus from 'Les Planes de Xàbia' (comparison scale in cm)

The FILMED project starts the field activities

Dr. Isabel Mateu, FILMED project coordinator, shows how the leaf samples of myrtle (Myrtus communis) must be harvested and prepeared in small bags containing silica gel.

April 2007. Photo credits: E. Laguna

During mid April 2007 the researchers working for the FILMED project started the field activities, picking up leaf samples from the 8 targeted species. Formerly, Dr Isabel Mateu, project coordinator, leaded a demonstration session to explain all the sampling protocol procedures. Each plant population must be sampled picking up leaf samples (1-5 healthy leaves, sometimes more depending on leaf size) of 10 plants -1 specimen each 50 or more meters, so sampling transects should cover if possible 500 or more meters-. Leaf samples are packed in bags containin g ca. 15 gr (approx. 2-3 medium-siz full spoons) of indicating silica gel, sealed and marked to indicate the origin, species and other needed data. The samples picking will continue during 2007 and 2008, but most leaves should be pickef up in spring, in order to catch the maximum ADN in the best conditions.

Overview of the sampling area for Pistacia lentiscus by the site 'El Salado' (El Viso, province of Córdoba, Andalousia) in Sierra Morena mountains. Vegetation is a mixed forest co-dominated by Quercus rotundifolia and Olea sylvestris and belongs to the climacic plant community Pyro bourgeani-Quercetum rotundifoliae pistacietosum lentisci, the so-called 'charnecal', climax vegetation for most part of the lowlands in the Luso-Extremadurian sector (SW Spain). Pistacia lentiscus is there a frequent species on the tall arbustive layer (each 'charneca' or P. lentiscus shrub is 3-4 m tall) and sometimes becomes a co-dominant species.
April 2007. Photo credits: E. Laguna

Welcome to our blog

We open this new blog on the phylogeography and related topics for common pan-Mediterranean species of wild plants. It is developed in the framework of the research project FILMED (nr CGL 2006-09427 BOS, granted by the Spanish Ministry of Research and Education in its public call 2006 for universities and research institutions) and deals with 8 major species (all af them considered 'sensu amplo'): Arbutus unedo, Celtis australis, Myrtus communis, Nerium oleander, Pistacia lentiscus, Quercus coccifera, Rhamnus alaternus, and Rosmarinus officinalis. However, information on any other species and/or on major topics about plant phylogeography also will be posted and discussed. Please remind that the blog is opened to express scientifical opinions and circulate news around these species and/or topics.