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 mostly in whorls of 5–8, entire or pinnatifid with 6–8 segments, 5–20 mm long. Stems often with short curled hairs. Mericarps cylindrical, up to 1 mm long, yellowish-brown to red, papillose. Coast. Still water or on mud Myriophyllum crispatum
Emerged leaves mostly in whorls of 3–6. Stems glabrous