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The reproductive biology of Grindelia covasii, a perennial resinous herb close to G. chiloensis and considered a potential industrial crop for arid lands, was studied. Flower phenology, pollinators and the breeding system were investigated. The species is limited to a very restricted area in Lihue Calel National Park, La Pampa Province, Argentina, and flowers from September to November. The capitula are primarily visited by bees, beetles, thrips and flies. It is self-incompatible and requires pollination for seed set. The array of visitors was compared with those to other Grindelia species. The species occurs in rather dense stands on rocky outcrops and any reduction of population size may have dramatic effects on reproductive output. This is unlikely to occur to G. covasii as all populations are located in a protected area. The importance of the introduction of the honeybee and the possible effect on natural pollinators is discussed. (C) 1999 Academic Press.