Proceedings of the Ohio State Academy of Science 85 



38. Bark of trunk and larger branches separating into paper}^ 

 or -leathery sheets; leaves doubly serrate, the lateral 

 veins ending in the main serrations, teeth or lobes. 



Betula. (18). 



38. Bark not in papery or leathery sheets; leaves not doubly 



serrate, the lateral veins not ending directly in the 

 serrations or teeth. Amelanchier. (40). 



39. Leaves not with spines. 40. 



39. Leaves evergreen, with spine-tipped lobes. Ilex. (54). 



40. Pith not solid, diaphragmed, with lenticular cavities. 41. 

 40. Pith solid but with prominent diaphragms ; vascular 



bundles 3 in the base of the petiole. Nyssa. (76). 



40. Pith solid, without diaphragms. 42. 



41. Leaves oval or obovate, serrate or denticulate, abruptly 



acuminate, wedge-shaped at the base, more or less 

 stellate pubescent beneath ; bark of twigs peeling ofif" 

 in slender shreds ; fruit 4-winged. Mohrodendron. (68). 



41. Leaves oblong or slightly obovate, acute or acuminate 



at both ends, crenate-serrate or repand, short petioled ; 

 twigs of the season and lower surface of leaves 

 pubescent, not stellate ; fruit a nut-like drupe. 



Symplocos. (67). 



42. Leaves with peltate scales, or resin-dotted, oblanceolate 



or wedge-lanceolate. Myrica. (13). 



42. Leaves not peltate scaly, nor resin-dotted. 43. 



43. Outer bud scales of winter buds more than i. 44. 



43. Outer bud scale i ; twigs with brittle zones, hence easily 



detached and leaving peculiar self-pruning scars : 

 terminal bud of ripe branches absent ; bundle scars or 

 vascular bundles in base of petiole. 3. Salix. (12). 



44. Pith decidedly 5-angled. 45. 



44. Pith cylindrical or nearly so. 46. 



45. Bundle scars 3 ; leaves with gland-tipped teeth, usually 



broad-based, usually with 2 prominent glands at the 

 base of the blade. Populus. (11). 

 45. Bundle scars several, scattered ; leaves without glands ; 

 buds clustered at the tip of the twig. Quercus. (22). 



