개불알풀속 Veronica LINN.

1. 꽃은 잎겨드랑이에 1 개씩 달리거나 포 같은 잎겨드랑이에 달려서 수상화서가 된다.

2. 다년초이다.

3. 줄기는 곧추 자라며 털이 있다  ······························································································· 338. 두메투구꽃

3. 줄기는 지면으로 벋으며 털과 선모가 있다 ························································································339. 방패꽃

2. 1-2년초이다.

4. 꽃은 액생한다.

5. 꽃과 열매의 자루는 1 mm 이내이다.

6. 줄기와 잎은 육질이며 털이 없거나 약간 선모가 있고 잎은 주걱형，장타원형 또는 선형이다 ························ 340. 문모초

6. 식물체는 육질이 아니며 털이 있다. 아래쪽의 잎은 난형이고 위쪽의 잎은 난상 장타원형이다 ·················· 341. 선개불알풀

5. 꽃과 열매의 자루는 5-30mm이다.

7. 잎의 톱니는 2~3쌍이다   ······································································································343. 개불알풀

7. 잎의 톱니는 3~5 쌍이다   ···································································································342. 큰개불알풀

4. 꽃은 연약한 액생 총상화서에 달린다.

8. 소화경은 길이 3mm로서 다소 위로 향하고 꽃차례의 지름이 8~12mm에 이른다    ·······························337. 큰물칭개나물

8. 소화경은 길이 4~6mm로 퍼져서 꽃차례의 지륨이 12~15mm에 이른다   ··············································336. 물칭개나물