CRATAEGUS 113 



broad as high, armed with slender 

 thorns or sometimes nearly thorn- 

 less. 



d. Bark comparatively thin and 

 smooth, exfoliating in small 

 thin flakes. 



Series 1. Microcarpae. (C. 



spathulata Michx.,etc.) 

 d. Bark on old boles or bran- 

 ches comparatively thick, 

 more or less fissured or 

 scaly. 



e. Thorns usually straight 

 and slender, 2-3. 5 cm. 

 long. No compound thorns. 



Series 4. Pulcherrimae. ( C. 

 ancisa Beadle, etc. ) 

 e. Thorns stouter, often 

 curved, 3-5 cm. long. 

 Compound thorns some- 

 times on boles and 

 larger branches. 



Series 3. Intricatae. (C. intricata 

 Lange, etc. ) 



b. Usually arborescent, but sometimes appear- 

 ing shrubby in young state. 



c. Boles and larger branches fluted or but- 

 tressed, not round or symmetrical in 

 cross section; thorns usually stout and 

 strongly curved. 



Series 9. Tenuifoliae. (C. 



macrosperma Ashe, etc.) 



c. Boles and larger branches norm- 

 ally terete and symmetrical in 

 cross section;thorns variable but 

 not conspicuously short and curved. 



d. Bark thin, pale gray, exfoliating in 

 large plates or flakes over orange- 

 brown or cinnamon colored inner 

 bark. Becoming large trees in low alluvial 

 ground; often thornless or sparingly thorny. 



Series 5. Virides. (C. viridis 

 L. , etc. ) 



