서나무속 Carpinus LINN.

1. 잎은 측맥이 15~20쌍이고 과수는 장타원형이며 포는 로 겹쳐지고 양쪽에 니가 다    ·······························74. 까치박달

1. 잎은 7~15 쌍이고 과포는 떨어져서 달라힌쪽에만 톱니가 있다

2. 잎은 길이. 4-12cm하고 과수의 는 밑부분라진다.

3. 잔가지는 이 있고 표면 엽맥 사이에 .

4. 8cm 과포길이 2.2 cm 이다 ·····································································75. 개서나무

4. 9~ 10.5 cm, 과포는 2.5 cm 이상이다   ······························································76. 왕개서나무

3. 잔가지는 털이 없거나 어릴 때 약간 털이 있고 잎은 표면에 털이 없다 ······················································ 77. 서나무

2. 잎은 길이 3~5cm로서 예두이고 과수의 포는 밑부분이 갈라지지 않거나 열편이 매우 작다·······························78. 소사나무