Roberto Gamarra

Heavy metals distribution in soils surrounding an abandoned mine in NW Madrid (Spain) and their transference to wild flora

The present work concerns the distribution and mobility of heavy metals (Fe, Mn, Cu, Zn and Cd) in the surrounding soils of a mine site and their transfer to wild flora. Thus, soils and plants were sampled from a mining valley in NW Madrid (Spain), and total and extractable heavy metals were analysed. Soils affected by mining activities presented total Cd, Cu and Zn concentrations above toxic thresholds. The percentage of extractable element was highest for Cd and lowest for Cu. A highly significant correlation was observed between the total and extractable concentrations of metals in soils, indicating that, among the factors studied, total metals concentration is the most relevant for heavy metals extractability in these soils. (NH(4))(2)SO(4)-extractable metal concentrations in soils are correlated better with metal concentrations in several plant species than total metals in soils, and thus can be used as a suitable and robust method for the estimation of the phytoavailable fraction present in soils. Twenty-five vascular plant species (3 ferns and 22 flowering plants) were analysed, in order to identify exceptional characteristics that would be interesting for soil phytoremediation and/or reclamation. High Cd and Zn concentrations have been found in the aerial parts of Hypericum perforatum (Cd), Salix atrocinerea (Cd, Zn) and Digitalis thapsi (Cd, Zn). The present paper is, to the best of our knowledge, the first report of the metal accumulation ability of the two latter plant species. The phytoremediation ability of S. atrocinerea for Cd and Zn was estimated, obtaining intervals of time that could be considered suitable for the phytoextraction of polluted soils.

Anacamptis versus Orchis (Orchidaceae): seed micromorphology and its taxonomic significance

Seed micromorphology of 24 taxa of the genera Anacamptis and Orchis was examined under light and scanning electron microscopy. Seed qualitative characters appear very useful at the supraspecific level in the subtribe Orchidinae. Based on our observations, the sculpturing of the periclinal walls of the medial testa cells, the seed shape and several features of the anticlinal walls of the apical cells showed variability between the studied taxa, with special relevance of the first character. According to this factor, we found one type of seed for Anacamptis and two for Orchis. The taxonomic value of seed coat characters is compared with the last taxonomic proposals for the genera Anacamptis and Orchis.

Evidence of a new Hg-tolerant ecotype of Rumex induratus from Almadén (Ciudad Real, Spain)

Mercury tolerance in wild vascular plants has hardly been studied and a tolerant ecotype is not known. In order to confirm the tolerance to Hg of Rumex induratus naturally growing in the biggest Hg mine in the world (Almadén population), the population was compared in a hydroponic experiment with another population from a non-Hg-contaminated area (Colmenar). The plants were exposed to different doses of Hg and a dose of As to establish whether the tolerance to Hg coincides with tolerance to other trace elements. Plants from Colmenar reached up to 1322 μg Hg g− 1 in roots and 65 μg Hg g− 1 in shoots and showed a significant decrease in biomass due to Hg exposure, whilst Almadén accumulated only 812 μg Hg g− 1 and 56 μg Hg g− 1 in roots and shoots, respectively. The Almadén population showed a higher tolerance to intense exposure to Hg, but not to As. Plants from Almadén exposed to Hg showed higher capacity to synthesise thiols in the root and to control oxidative stress and Zn starvation. Our findings suggest that R. induratus could be used to enhance understanding of the mechanisms of Hg tolerance in plants.

Novedades corológicas y taxonómicas sobre orquídeas ibéricas

Se recogen datos corologicos de 11 especies de Orchidaceae en el territorio iberico, de los cuales un buen numero suponen novedades provinciales. Tambien se realizan diversos comentarios sobre su presencia en esta area geografica y acerca de su taxonomia.

Seed micromorphology of Orchidaceae in the Gulf of Guinea (West Tropical Africa)

Qualitative micromorphological characters of seeds were analysed using Scanning Electron Microscopy for 95 species of 34 genera, belonging to the subfamilies Vanilloideae, Orchidoideae and Epidendroideae (Orchidaceae) from the Gulf of Guinea countries. Three genera (Dinklageella, Platylepis and Rhipidoglossum) and 69 species were studied for the first time. Vanilla shows a pattern of seed coat distinct to the rest of the studied taxa. Orchidoideae and Epidendroideae show variation in several features: seed shape, orientation of testa cells, morphology of anticlinal walls, cell corners, shape and ornamentation of the periclinal walls and presence of waxes. Two main patterns have been observed: one with parallel medial cells along the longitudinal axis, thin and straight anticlinal walls, with no raised and no thickened cell corners, wide periclinal walls and lack of waxes, for the terrestrial orchids of the subfamily Orchidoideae, the tribes Tropidieae, Nervilieae, Collabieae, Cymbidieae and the subtribe Malaxidinae (Epidendroideae); the other one showed twisted medial cells, thickened anticlinal zone with prominent ridges, raised and thickened cell corners, narrow-to-not visible periclinal walls and presence of waxes, in epiphytic orchids of Vandeae, Podochileae and Dendrobiinae (Epidendroideae). In the epiphytic genera Ansellia and Graphorkis (Cymbidieae) and in Liparis epiphytica (Malaxideae), thickened anticlinal walls and presence of waxes also occurred but parallel medial cells along the longitudinal axis and wide periclinal walls have been observed. This study confirms the diagnostic value of the qualitative features of the seed coat in Orchidaceae and suggests a probable relation with adaptations to habitat for seed dispersal.