Biogeochemical studies of metal-tolerant plants from southern Morocco

An expedition to Southern Morocco was undertaken to study and collect the poorly documented metal-tolerant flora of the Bou Azzer region. The areas visited are underlain by ultramafic rocks with associated cobalt-nickel arsenide mineralization and chromium carbonates (Bou Azzer), and by volcano-sedimentary rocks with associated copper sulphide mineralization (Bléida). Biogeochemical studies were made of metals in many species, of which the five most common are Anvillea garcinii subsp. radiata, Ononis natrix (goat-root), Laiandula multifidia (lavender), Convolaulus trabutianus (morning-glory), and Artemisia herba-alba (sagebrush). Results show differences in the ability of each species to accumulate metals. Ononis concentrates most of the ore-forming elements to highest levels. However, because of its more widespread occurrence, Anuillea is a more appropriate sample medium for biogeochemical surveys. From chemical analysis of its stems, zones of concealed mineralization can be identified where conventional soil analysis is less definitive.