Stopps, G. J., White, S. N., Clements, D. R. and Upadhyaya, M. K. 2011. The Biology of Canadian weeds. 149.Rumex acetosellaL. Can. J. Plant Sci. 91: 1037-1052. Rumex acetosella L., sheep sorrel, is a perennial herb originating from Europe and southwestern Asia, now found in at least 70 countries worldwide. A common weed, it appears in grasslands, pastures, rangelands, waste areas, and along roadsides across North America. It frequently occurs as a weed in lowbush blueberry fields in Atlantic Canada, particularly in Nova Scotia. Rumex acetosella thrives on poor, acidic, and disturbed soils across a broad range of climatic conditions. A persistent seed bank and vegetative reproduction from creeping roots contribute to the ability of R. acetosella to tolerate various methods of control including certain herbicides, fire, and tillage. Tart-tasting leaves, rich in vitamin C have led to the use of R. acetosella in European and North American cultures as both a source of food and a component of herbal medicines. Excessive consumption of the leaves, which contain oxalic acid, can be poisonous to horses and sheep. In addition, R. acetosella is a possible host of the tomato spotted wilt virus, which is detrimental to a variety of vegetable crops.