자작나무과 Betulaceae

1. 견과에 잎 같은 총포가 없다.

2. 열매의 포린은 떨어지지 않고 5 개로 갈라진다 ·····················································································오리나무속

2. 포린은 3 개로 갈라졌으며 성숙하면 떨어진다  ·····················································································자작나무속

1. 열매는 잎 같은 총포로 싸여있다.

3. 열매는총생하고 겨울눈은 둔두이며 웅화수는 겨울 동안에 노출된다····· ······················································ 개암나무속

3. 열매는 이삭처럼 달리고 겨울눈은 끝이 뾰족하다.

4. 열매의 총포는 퍼지고 톱니가 있으며 웅화수는 봄철에 자란다 ···································································서나무속

4. 열매의총포는 주머니같고 웅화수는 겨울에 노출된다···································································새우나무속 Ostrya

5. 잔가지에는 털과 선모가 밀생한다 ·····························································································79. 새우나무

5. 잔가지에는 선모가 거의 없다  ····························································································79+. 좀새우나무