Elodea canadensis, called broad waterweed in Dutch, originates from North America. This submerged, evergreen aquatic plant with stems of 60cm and more has an enormous water-purifying capacity and vigor. It quickly forms runners and can form entire mats in a short time. The leaves are oblong, lanceolate, dark green, usually in whorls of 3 on the long stems. Elodea is dioecious, but in our regions we usually only find female plants. The flowers are inconspicuous, greenish white to pinkish, the flowering period runs from May to August. Waterweed likes a place with sufficient sunlight and prefers to grow in a mixture of clay and peat, but it also comes into its own in a sandy soil.