물통이속 Pilea LINN.

1. 잎 뒷면에 갈색 선점이 있고 3 개의 암꽃 화피 중 1 개가 길다 ······································································153. 물통이

1. 잎 뒷면에 잔점이 없다.

2. 암꽃 화피는 3개로 갈라진다.

3. 암꽃 화피열편은 길이가 비슷하다 ····························································································154. 모시물통이

3. 암꽃 화피열편 중에서 1 개가 짧다.

4. 잎은 길이 15mm 이상이고 열매에 적갈색 반점이 있다···································································· 155. 큰물통이

4. 잎은 길이 15mm 이하이다.

5. 잎자루는 길이 2~17mm 이고 열매에 갈색 점이 있다  ···························································· 156. 제주큰물통이

5. 잎자루는 길이 3-8m, 잎은 길이 5~12mm 이다····································································· 157. 강계큰물통이

2. 암꽃 화피는 5 개로 갈라진다  ········································································································ 158. 산물통이