IfS Field Manual 



—37— 



•"^7. Leaves 2-ranked. 38. 



37. Leaves not 2-ranked. 39. 



38. Bark of trunk and larger branches separating into 



papery or leathery sheets; leaves doubly serrate, the 

 lateral veins ending in the main serrations, teeth 

 or lobes. Betula. (59). 



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



doubly serrate, the lateral veins not ending directly 

 in the serrations or teeth. Amelanchier. (25). 



39. Leaves not with spines. 40. 



39. Leaves evergreen, with spine-tipped lobes. Ilex. (36). 



4<>. Pith not solid, diaphragmed, with lenticular cavities. 4L 



4<». Pith solid but with prominent diaphragms; vascular 

 bundles 3 in the base of the petiole. Nyssa. (81). 



4u. 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. 



Halesia. (72). 



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. (71). 



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



late or wedge-lanceolate. Myrica. (63). 

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



43. Outer bud scales of winter buds more than 1. 44. 



43. Outer bud scale 1; 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. (65). 



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. (64). 



