원추리속 Hemerocallis LINN.

1. 꽃은 등황색 또는 등적색이고 낮에 피며 뿌리의 일부는 방추상이다.

2. 소화정은 거의 없거나 짧으며 1 꽃차례에 2-4개의 꽃이 달린다. 꽃줄기와 잎의 길이는 거의 비슷하다.

3. 포는 난형 내지 난상 피침형이며 길이 18-20mm 이다 ····································································580. 각시원추리

3. 포는 넓은 난형이고 끝이 꼬리같이 길며 길이 2-3cm 이다 ·································································581. 큰원추리

2. 소화경은 짧고 꽃줄기가 잎보다 훨씬 길다.

4. 잎은 상록이고 꽃은 짙은 등적색이다 ························································································582. 홍도원추리

4. 잎은 겨울에 마른다.

5. 잎은 너비 1.2-2.5cm 이고 길이 60-80cm 이다.

6. 꽃잎은 단엽이다 ················································································································· 583. 원추리

6. 꽃잎은 만첩이다 ·············································································································· 584. 왕원추리

5. 잎은 길이 40cm 이하이고 너비 1cm 이하이다.

7. 뿌리 끝에 방추상 덩이뿌리가 달리고 꽃은 많이 달리며 넓은 난형상타원형이다 ·································· 585. 골잎원추리

7. 뿌리 끝에 방추상 덩이뿌리가 없거나 간혹 있고 꽃은 2-3(간혹그이상) 이며 삭과는 좁은 타원형이다 ············· 586. 애기원추리

1. 꽃은 저녁때 피고 담황색이며 방추상 덩이뿌리가 없다 ·········································································· 587. 노랑원추리