Controlled weeds (Elodea canadensis)
|Canada waterweed (Elodea canadensis)||Canada waterweed is a very invasive perennial. Although it sometimes reaches the water surface, it usually grows horizontally, forming a dense carpet. Thus making it a serious nuisance. Its stem and leaves are completely submerged.The plant anchors itself to the bottom by means of roots that develop along the stem and the stolon (a stem growing along the ground like a strawberry runner). These roots can reach impressive lengths (nearly 50 cm), but they are sparse and are anchored less than 15 cm in the soil. On average, Canada waterweed is one meter long.
While Canada waterweed can reproduce by seed formation or budding, its usual means of propagation is by fragmentation. Pieces of stem detached from the plant are carried away by the water and take root, colonizing a new part of the waterway. Pulling the plant out will not keep it from growing somewhere else.
Canada waterweed grows best in muddy or sandy soil. Beaches and marinas thus make ideal habitats. Canada waterweed gather nutrients directly from the water via its leaves; it also feeds on sediments.
Canada waterweed thrives in nutrient-poor waters, but these water are far from being its only habitat. It is among the species with the best tolerance for highly eutrophic (nutrient-rich) waters. It is usually found in calm waters or areas where the current is weak, and rarely in strong currents, due to its underdeveloped root system and its need for fine soil.