Comparison of Sensitivity of Grasses ( Lolium perenne L. and Festuca rubra L.) and Lettuce ( Lactuca sativa L.) Exposed to Water Contaminated with Microcystins. - Pereira, Silvia; Saker, Martin L.; Vale, Micaela; Vasconcelos, Vitor M. (Bulletin of Environmental Contamination & Toxicology, 2009)