피나무과 Tiliaceae

1. 목본식물이다.

2. 교목으로서 꽃차례 밑에 큰 포가 있다 ···································································································· 피나무속

2. 관목이다   ···························································································································1152. 장구밥나무

1. 초본식물이다.

3. 열매에 가시가 밀생한다   ········································································································1153. 고슴도치풀

3. 열매에 가시가 없다    ······················································································································1154. 황마

피나무속 Tilia LINN.

1. 잎은 뒷면 맥 상이나 맥액에 털이 있거나 전체에 갈색 털이 있다.

2. 잎은 뒷면 전체에 갈색 털이 있거나 양면 맥 상에 잔털이 있다.

3. 잎은 양면 맥 상에 잔털이 있고 맥액에 황갈색 털이 있다  ······························································· 1141. 구주피나무

3. 잎은 뒷면 전체에 갈색털이 있고 열매는 둥글다   ············································································ 1142. 털피나무

2. 잎은 뒷면 맥상 또는 맥액에 털이 있다.

4. 잎은 뒷면 맥상에 흰 털이 있거나 없다   ······················································································· 1143. 섬피나무

4. 잎은 뒷면 맥액에 갈색 털이 있다.

5. 과지의 잎은 길이 4-9cm이다.

6. 열매는 둥글거나 도란형이며 능선이 없다  ········································································· 1144. 피나무(달피)

6. 열매는 넓은 난형이며 능선이 있다  ··················································································· 1145. 연밥피나무

5. 과지의 잎은 길이 3-4cm 이다   ·························································································· 1146. 뽕잎피나무

1. 잎은 뒷면에 희고 짧은 성모가 밀생한다.

7. 열매에 능선이 없다.

8. 열매는 둥글다  ···················································································································· 1147. 찰피나무

8. 열매는 난형이다  ··············································································································· 1148. 웅기피나무

7. 열매에 능션이 있다.

9. 열매의 능선은 기부에서부터 끝까지 닿아있다 ··············································································· 1149. 염주나무

9. 열매의 능선은 기부에서부터 중앙까지만 있다.

10. 잔가지 · 잎자루 및 꽃자루에 회갈색 털이 밀생하고 열매의 능선은 중앙이하까지 발달한다····················· 1150. 개염주나무

10. 잔가지 · 잎자루 및 꽃자루에 회백색 털이 있고 열매의 능선은 밑부분에만 있다 ·································· 1151. 보리자나무