산사속 Crataegus LINN.

1. 잎은 깃처럼 갈라지고 안쪽 가장자리를 따라 달린 맥이 있다 ········································································· 821. 산사

1. 잎은 양은 결각상 또는 손바닥모양으로 갈라지고 안쪽 가장자리를 따라 달린 맥이 없다.

2. 잎은 결각상으로 갈라진다.

3. 가시는 길이가 2cm 이하로서 곧고 잎의 뒷면에 털이 밀생한다 ···························································· 822. 아광나무

3. 가시는 길이 3~5cm 로서 뒤로 젖혀지고 잎 뒷면에 털이 없다 ····························································· 824. 미국산사

2. 잎은 손바닥모양으로 갈라진다 ·································································································· 823. 이노리나무