Country of Origin: cosmopolitan, native to all continents except Antarctica.
Habitat: submerged, free-floating aquatic plant
Description: Ceratophyllum demersum has whirled leaves which are densely crowded at the apex of beautifully branched stems, whereas internodes may exceed 3 cm in length at the base of older stems. Ceratophyllum demersum is an obligate submerged perennial plant which does not form roots. In Nature it is usually found buried in sandy to silty sediments where it anchors itself by modified leaves. Ceratophyllum demersum often forms monospecific populations and is found down to 10 m depth as individual very slow-growing plants. In the aquarium, on the other hand, it prefers relatively high light, and it does not tolerate transportation for extended periods. It excretes substances toxic to algae (allelopathic behaviour) and at good growth conditions it efficiently inhibits most algae growth.