xii 



43a. Lateral leaf-veins straight and parallel, and terminating in the 

 teeth BETULACEAE, p. 21. 



3b. Lateral veins more or less curved, and not ending in the teeth 

 44. 



44a, Leaves palmately veined, about as broad as long; juice 

 somewhat milky 2b, in URTICACEAE, p. 23. 



44b. Leaves pinnately veined; juice not milky 45. 

 45a. Willows, with slender leaves and brittle twigs 



8a, in SALICACEAE, p. 19. 

 45b. Trees with lanceolate, ovate, or oblong leaves and tough twigs 



30, in ROSACEAE, p. 54. 

 45c. Cottonwoods, with broad, heart-shape or rounded leaves 



la, in SALICACEAE, p. 19. 



46.a. Petioles laterally compressed 2a, in SALICACEAE, p. 19. 



46b. Petioles not compressed; lateral veins straight and parallel, 



running directly to the teeth FAGrACEAE, p. 22. 



47a. Stem thorny 41bf in ROSACEAE, p. 54. 



47b. Stem not thorny 48. 



48a. Leaves palmately veined 49. 

 48b. Leaves pinnately veined 51. 



49a. Lobes of the leaf entire lb, in LAURACEAE, p. 41. 



49b. Lobes of the leaf serrate 50. 



50a. Juice somewhat milky; lateral buds visible 



2b, in URTICACEAE, p. 23. 



50b. Juice not milky; lateral buds covered by the base of the 



P etiole PLATANACEAE, p. 51. 



51a. Leaves with 4 large entire lobes; stem marked with a ring at 



each node 3IAGNOLIACEAE, p. 40. 



51b. Leaves with many lobes; stem not ringed 



lb, in FAGACEAE, p. 22. 



. 52 



52a. For specimens bearing leaves only 53. 

 52b. For specimens bearing flowers only 140. 

 52c. For specimens with both leaves and flowers 155. 

 53a. Leaves narrow, needle-like or scale-like, mostly evergreen 54. 

 53b. Leaves broader, flat or rolled, but not needle-like or scale-like 

 56. 



54a. Foliage densely gray-pubescent; low bushy shrubs with 

 yellow flowers 2a, in CISTACEAE, p. 74. 



54b. Foliage green 55. 



55a. Leaves opposite or whorled PltfACEAE, p. 1. 



55b. Leaves scattered on the stem TAXACEAE, p. 2. 



56a. Twining or climbing vines 57. 



56b. Not climbing or twining 66. 



