올방개속 Eleocharis R. BR.

1. 화수는 원주형이며 꽃줄기의 굵기와 같다. 속이 비었고 횡격막이 있거나 스폰지형이며 화수는 길이 2~4cm 이다.

2. 인편은 길이 5~6mm로서 백록색이며 끝이 절두이다    ············································································389. 남방개

2. 인편은 황록색 또는 볏짚색이며 길이 6-8mm로서 끝이 둥글고 뾰족하다 ·······················································390. 올방개

1. 화수는 난형 또는 타원형이며 꽃줄기보다 굵고 꽃줄기는 충실하다.

3. 암술머리는 3 개이다.

4. 꽃줄기는 털같이 가늘고 포복경이 있다 ····························································································391. 쇠털골

4. 꽃줄기는 실같이 가늘고 포복경이 없다.

5. 화수는 길이 2-4mm 이고 지름 1.5-2.5mm 이다  ············································································ 392. 바늘골

5. 화수는 길이 1-2.5 cm，지름 4-5mm 이고 연편은 길이 2.5-4mm 이다.

6. 화수는 길이 1-2.5cm, 지름 4.5-6mm이고 화피 열편에 깃 같은 털이 있다  ·········································· 393. 네모골

6. 화수는 길이 7-10mm, 지름 3mm이며 화피 열편은 돌기가 없고 밋밋하다  ·········································· 394. 참바늘골

3. 암술머리는 2 개이다.

7. 소수 밑의 인편 1 개는 비어있다  ····························································································395. 올방개아재비

7. 소수 밑의 2-3 개 인편은 꽃이 없다.

8. 꽃줄기는 굵고 연하며 밝은 녹색이고 마르면 편평해진다. 정소수는 둔두이다    ····································· 396. 물꼬챙이골

8. 꽃줄기는 다소 가늘고 굳으며 회록색이다. 말라도 편평하게 되지 않으며 소수는 짧은 예두이다   ······················ 397. 까락골