Myriophyllum L.
Aquatic plants or growing on mud. Petals absent in female flowers Myriophyllum
At least submerged leaves whorled or opposite
At least submerged leaves in whorls of 3–8
Emerged leaves thick, flat or compressed, lanceolate to narrow-elliptic or ovate to oblong
Mericarps cylindrical, densely spinose, olive brown, c. 1.5 mm long. Emerged leaves glaucous, often red at tip, entire, 6–10 mm long, up to 3 mm wide. Widespread. Lakes and slow moving streams. Cat-tail Myriophyllum caput-medusae