2. 택사목 Alislnatales

1. 씨방상위이다.

2. 화피는 꽃받침 같거나 1 줄로 달린 꽃잎형이며 때로는 없기도 하다.

3. 화피가 있다.

4. 화피 열편은 2 개로서 단성화이다   ···············································································나자스말과 Najadaceae

4. 화피 열편은 6 개로서 양성화이다 ···············································································지채과 Scheuchzeriaceae

3. 화피가 없다(뿔말의 암꽃에는 있음).

5. 꽃은 양성이지만 간혹 단성도 있으며 수술은 2~4개로서 수술대는 꽃잎 같다   ························가래과 Potamogetonaceae

5. 꽃은 단성이고 불염포 안에 달리며 수술은 1 개이고 암꽃에 화피 열편이 3 개 있다  ·····················거머리말과 Zosteraceae

2. 외화피는 꽃받침 같고 내화피는 꽃부리같이 생겼다 ·····································································택사과 Alismataceae

1. 씨방하위이다   ···········································································································자라풀과 Hydrocharitaceae