개미탑과 Halorrhagaceae
1. 육상과 물속에서 자라며 줄기의 일부가 나무같이 단단하다 ······································································ 1299. 개미탑
1. 수생식물이며 줄기가 단단하지 않다 ···································································································· 물수세미속
물수세미속 Myriophyllum LINN.
1. 꽃차례는 수상이며 공중에 나온 꽃차례에 잎이 없다 ······································································· 1300. 이삭물수세미
1. 공중에 나온 꽃차례에는 잎이 달린다.
2. 공중애서
자라는 잎은 갈라지지 않는다 ······················································································ 1301. 선물수세미
2. 공중에서
자라는 잎은 깃처럼 갈라진다 ························································································· 1302. 물수세미