쓴풀속 Swertia LINN.

1. 뿌리에서 돋은 잎은 줄기에 달린 잎보다 작다.

2. 꽃잎은 4수이며 밀선구는 1 개이다.

3. 꽃잎에 흑자색 점이 있다  ·······································································································113. 네귀쓴풀

3. 꽃잎에 점이 없다 ·················································································································114. 큰잎쓴풀

2. 꽃잎은 보통 5개이고 밀선구는 2개이다.

4. 꽃받침잎은 피침형 또는 넓은피침형이며 밑이 다소 좁아진다. 잎은 도피침형이고너비 3-10mm로서 끝이 둔하며 식물체에 쓴맛이 없다 ········· 115. 개쓴풀

4. 꽃받침잎은 선형 또는 넓은선형이며 밑이 좁아지지 않는다. 잎은 너비 1 ~5mm (8mm)이고 식물체에 쓴맛이 있다.

5. 줄기 · 꽃받침잎 및 소화경에 작은 돌기가 있다. 식물체는 자줏빛이 도는 것이 많고 밀선구의 털은 구불구불하다 ···························· 116. 자주쓴풀

5. 식물체는 평활하고 밀선구 주위의 털은 밋밋하다 ················································································ 117. 쓴풀

1. 뿌리에서 돋은 잎은 잎자루가 길고 줄기에 달린 잎도 비교적 크다 ···································································118. 별꽃풀