The Biology of Canadian Weeds. 153. Stachys palustris L

Marsh hedge-nettle, Stachys palustris, is a perennial Eurasian member of the mint family, which has become naturalized and weedy in some parts of eastern North America. It is a hexaploid member of a holarctic species complex, which differs morphologically from the primarily tetraploid North American forms. The production of fleshy tuberous rhizomes is the most significant distinctive feature. In Canada, it has been a weed of potato and root crops in Nova Scotia, New Brunswick and Prince Edward Island, although other crops and areas, such as soybean in Ontario, are also affected. Usually considered a wetland plant, it readily spreads into drier arable fields from adjacent ditches and wetlands. Several herbicides available for use in Canada have been found to provide limited long-term suppression in agricultural systems, with the best results obtained using combined pre-emergent and post-emergent applications.