92 



STEM OP EXOGENS. 



Bamboos, Canes, and many other hard-stemmed and lofty tribes, 

 inhabiting tropical climates ; but scarcely any except herbaceous 



FIG. 39. AGAVE AMERICANA ; ENDOGEN. 



plants belonging to this division, exist in temperate regions ; the 

 chief tribes which it includes in this country being the Lilies, 

 with most other bulbous-rooted plants, and the Grasses. To the 

 second belong all the trees and shrubs, and a large proportion of 

 the plants, of temperate climates ; whilst between the tropics, 

 its place is partly occupied by the other. The last, as being the 

 best known in this country, will be first described. 



126. If we cut across a young twig of any common tree or 

 shrub, such as the Ash, Elder, &c. we shall observe that it con- 

 sists of three distinct parts, ordinarily known as the Pith, 



