대극속 Euphorbia LINN.

1. 목본식물이다 ························································································································ 1051. 포인세티아

1. 초본식물이다.

2. 잎은 대생 또는 윤생한다.

3. 잎은 윤생한다 ························································································································· 1041. 낭독

3. 잎은 대생한다.

4. 식물체는 비스듬히 서며 잎은 길이 1~3cm 이고 열매에 털이 없다 ·················································· 1043. 큰땅빈대

4. 식물체는 지면을 기어가며 잎은 길이 15mm 이하이다.

5. 잎에 반점이 없고 열매에 털이 없다 ························································································ 1044. 땅빈대

5. 잎에 반점이 있고 열매에 털이 있다 ··················································································· 1045. 애기땅빈대

2. 잎은 꽃차례 이외에는 호생한다.

6. 꽃차례의 선체 끝이 둥글다.

7. 2 년초이며 잎 끝이 파진다 ····································································································· 1046. 등대풀

7. 다년초이다.

8 잎에 톱니가 있고 꼬부리진 털이 있다 ·························································································· 1047. 대극

8. 잎에 톱니가 없다.

9. 측맥이 희미하며 잎은 총생하고 가장자리에 흰 부분이 있다.

10. 줄기는 굵으며 잎은 끝이 둔하거나 둥글고 길이 4~7cm 이며 해안산이다 ······································ 1048. 암대극

10. 줄기는 가늘며 잎은 길이 5~20mm이고 톱니가 있으며 높은 산에서 자란다  ·································1040. 두메대극

        9. 측맥이 보이며 잎 가장자리에 흰 부분이 거의 없다  ·····································································1042. 붉은대극

  6. 꽃차례의 선체 끝이 뾰족하거나 둔하다.

    11. 배상화서의 선체 끝이 둔하며 꽃이 달리지 않는 가지에서는 잎이 총생한다  ············································1049. 흰대극

    11. 배상화서의 선체가 뿔같이 뾰족하다  ···························································································1050. 개감수