1. Bulblet-bearing Water-hemlock, Bulbous Water-hemlock: Cicuta bulbifera - Plants with bulbils borne in the axils of the reduced upper leaves. Leaflets of the main leaves narrowly linear, measuring 0.5-4 cm long and 0.5-1.5 mm wide. Fruits 1.5-2 mm long.

2. Douglas' Water-hemlock, Western Water-hemlock: Cicuta douglasii - Plants lacking bulbils in the axils of the upper leaves. Leaflets of the main leaves are 3-10 cm long and 5-35 mm wide. Fruits 2-4 mm long.

3. Spotted Water-hemlock, Spotted Cowbane: Cicuta maculata (varieties angustifolia, bolanderi, and maculata) -