메꽃속 Calystegia R BR.

1. 줄기는 옆으로 벋어간다.

2. 잎은 신원형이며 바닷가에서 자란다 ································································································ 161. 갯메꽃

2. 잎은 길이가 너비보다 길다.

3. 꽃자루는 위쪽에 좁은 날개가 있고 포는 예두이다  ···········································································162. 애기메꽃

3. 꽃자루는 위쪽에 날개가 없다.

4. 잎은 좁은 장타원형 둔두이며 포는 둔두 또는 요두이다 ·········································································163. 메꽃

4. 잎은 3각상 난형 예두이며 포는 둔두 또는 다소 예두이다 ··································································· 164. 큰메꽃

1. 줄기는 비스듬히 선다  ···················································································································· 165. 선메꽃