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 3–6. Stems glabrous
Mericarps cylindrical, c. 1.5 mm long, yellowish-brown. Emerged leaves strictly whorled, usually in 5s, 8–15 mm long, mostly entire. Stigmas white. Widespread. Still or slow moving water Myriophyllum variifolium
Mericarps ovoid, c. 1 mm long, reddish-purple. Emerged leaves often irregularly whorled, usually in 3s or 4s, 5–15 mm long, mostly entire. Stigmas red or pink. Coast and Cumberland Plain. Still water or on mud Myriophyllum simulans