ST. LAWRENCE INFO

Purple Loosestrife, Lythrum salicaria

Purple Loosestrife is a very widespread perennial that mainly invades the highest part of marshes. Its square, rigid stem with its often woody root mass and its purple flowers easily distinguish it from other plants.

	Lythrum salicaria a. Upper portion of plant b. Flower
Source: Crow and Hellquist 2000.

Location in the St. Lawrence River and Current State of Knowledge

Purple Loosestrife has been present in the area for a long time. The first specimen was harvested in 1883 near Quebec City. Purple Loosestrife is now abundant throughout the St. Lawrence Lowlands and is the alien species most often sampled in St. Lawrence River quadrats. It is very abundant in Lake Saint-François (in 57% of sites), decreases toward Contrecoeur (26%) and increases again in Lake Saint-Pierre (39%). Nevertheless, it only dominates in 9% of cases and its impact on plant diversity does not seem marked.

To Know More about the Purple Loosestrife

Canadian Wildlife Service – Invasive Plants of Natural Habitats in Canada

Literature

Crow, G.E. and C.B. Hellquist. 2000. Aquatic and Wetland Plants of Northeastern North America: A Revised and Enlarged Edition of Norman C. Fassett’s A Manual of Aquatic Plants. Volume One – Pteridophytes, Gymnosperms and Angiosperms: Dicotyledons. The University of Wisconsin Press, Madison, WI. 480 pages.

Crow, G.E. and C.B. Hellquist. 2000. Aquatic and Wetland Plants of Northeastern North America: A Revised and Enlarged Edition of Norman C. Fassett’s A Manual of Aquatic Plants. Volume Two – Angiosperms: Monocotyledons. The University of Wisconsin Press, Madison, WI. 400 pages.

Delisle, F., C. Lavoie, M. Jean, and D. Lachance. 2003. Reconstructing the spread of invasive plants: Taking into account biases associated with herbarium specimens. Journal of Biogeography 30: 1033–1042.

Groupe Fleurbec. 1987. Plantes sauvages des lacs, rivières et tourbières. Groupe Fleurbec, Montreal, Canada. 400 pages.

Jean, M., G. Létourneau, and C. Savage. 2005. Freshwater Wetlands and Exotic Plant Species: 2^nd edition. Fact sheet in the “Monitoring the State of the St. Lawrence” series. Environment Canada – Quebec Region and Ministère du Développement durable, de l’Environnement et des Parcs du Québec.

Jean, M., G. Létourneau, C. Lavoie, and F. Delisle. 2002. Freshwater Wetlands and Exotic Plant Species. Fact Sheet in the series “Monitoring the State of the St. Lawrence River.” Environment Canada – Quebec Region, Environmental Conservation, St. Lawrence Centre and Laval University, Centre de recherche en aménagement et développement.

Lavoie, C., M. Jean, F. Delisle, and G. Létourneau. 2003. Exotic plant species of the St. Lawrence River wetlands: A spatial and historical analysis. Journal of Biogeography 30: 537–549.

Marie-Victorin, F.E.C. 1997. Flore laurentienne, 3^e édition mise à jour et annotée, 1995. Les Presses de l’Université de Montréal, Montreal, Canada. 1093 pages.

White D.J., E. Haber, and C. Keddy. 1993. Invasive Plants of Natural Habitats in Canada. Environment Canada, Canadian Wildlife Service, Ottawa, Canada. 121 pages.