June, 1905.] Key to the Genera of Ohio Woody Plants. 365 



12. Leaves serrate, dentate, crenate, pinnatifid, or variously lobed. 31. 



13. With stipular rings at each leaf node; leaves large. Magnolia. 



13. Base of petiole covering the axillary bud and twigs with peculiar 

 rings but not at the leaf nodes. Dirca. 



13. Not with stipular rings; base of petiole not covering the axillary 



bud. 14. 



14. Leaves evergreen, some on wood of the previous season. 15. 



14. No leaves on wood of the previous season. 18. 



15. Leaves glabrous; erect shrubs or small trees. 16. 



15. Leaves hirsute or pubescent; low trailing or spreading shrubs. 17. 



16. Leaves green on both sides, thick, coriaceous, oblong to oblance- 



olate, 5-10 in. long; winter buds very scaly. Rhododendron. 



16. Leaves green on both sides, or glaucous beneath, coriaceous, 2-5 in. 



long; oval or oval-lanceolate, winter buds naked. Kalmia. 



17. Leaves oval or nearly orbicular, hirsvite beneath; twigs hirsute; 



prostrate shrubs. Epigaea. 



17. Leaves spatulate, minutely pubescent, with hairs on the margins; 



trailing or spreading shrubs. Arctostaphylos. 



18. With thorns; either small trees with milky sap or low vine-like 



shrubs. 19. 



18. A^Vithout thorns. 20. 



19. Trees or erect shrubs with prominent thorns; leaves with milky sap, 



the base obtuse, truncate, or cordate. Toxylon. 



19. Climbing shrubs with axillary thorns; leaves not milky, narrowed 



into short petioles. Lycium. 



20. Pith with prominent diaphragms but solid ; vascular bundles in 



base of petiole 3-7. 21. 



20. Pith not diaphragmed but sometimes with cavities. 22. 



21. Leaves 2-ranked; bark with fetid odor; vascvilar bundles in base of 



petiole 5-7. Asimina. 



21. Leaves not 2-ranked; vascular bundles in base of petiole 3. Nyssa. 



22. Leaves resin-dotted, waxy-dotted or punctate. 23. 



22. Leaves not dotted or punctate. 24. 



23. Shrubs or small trees; leaves oblong-lanceolate, spatulate, or 



oblanceolate, short pointed, narrowed at the base. Myrica. 

 23. Shrubs with obovate or elliptic leaves narrowed at the base; bark 

 spicy aromatic; axillary buds superposed. Benzoin. 



23. Low shrubs; leaves ovate-lanceolate, wedge-shaped at the tip. 



Gaylussacia. 



24. Pith prominently 5-angled ; leaves with deciduous stipules and with 



bristle tips; trees. Quercus. 

 24. Pith cylindrical or nearly so ; leaves downy with prominent 

 deciduous stipules. Cydonia. 



24. Pith cylindrical or nearly so; no stipules or stipular scars, if with 



minute stipules then glabrous. 25. 



25. Leaves with the upper 2 lateral veins more or less parallel with the 



midrib. Cornus. 



25. Leaves pinnately veined to the tip. 26. 



26. Bark when cut very resinous, fragrant; pith large, usvially brown. 



Cotinus. 



26. Bark not resinous. 27. 



27. Trees, sometimes with cavities in the pith; leaves oval or ovate, 



acute or acuminate, the petioles loosely jointed with the twigs. 



Diospyos. 

 2'~. Pith not with cavities; shrubs. 28. 



28. Leaves with long petioles; twigs not clustered and the leaf inter- 



nodes rather uniform, with minute stipules, llicioides. 



