(76) 



15. Horizontal cut of the bud of Celtis. 



16. Horizontal cut of the bud of Populus. 



17. Horizontal cut of the bud of Crataegus. 



18. Horizontal cut of the leaf of Carya alba. 



19. Diagram of the phyllotaxis of Quercus. 



20. Diagram of the phyllotaxis of Juglans. 



21. Diagram of the ^phyllotaxis of Ptelea. 



22. Diagram of the phyllotaxis of Amorpha. 



Note. — In these drawings the chief characteristics of these species are exposed, 

 but it must not be expected that every specimen compared with the fig'ure must 

 exactly agree; there is much variation in the form of the leaf- scars within certain 

 limits in the form of the buds, in the pubescence, etc. Not every twig of the 

 hazel is so glandular hairy as the figure shows, not in every twig of the blue ash 

 or burning bush, do we find the wings as in our figures, these are often only faint 

 lines. 



