THE CHAEACTEKISTICS OF TREES. 



19 



CHAPTER 11. 



THE CHARACTERISTICS OF TREES. 



The trees of the world are separated by botanists into 

 two grand divisions, known as exogens or outside growers 

 and endogens, or inside growers. These two divisions 

 are also called dicotyledon- 

 ous and monocotyledonous, 

 the first having two cotyle- 

 dons or seed-leaves, as seen 

 in the sprouting acorn or 

 young maple (fig. 1) the 

 two lower leaves being the 

 cotyledons), and similar tree 

 seeds, while the others have 

 but one cotyledon or seed- 

 leaf, as seen in the cocoa- 

 nut, date, and other species 

 of palms. As we have but 

 two or three arborescent 

 species of the palm, and a 

 yucca or two that reaches a 

 hight of even small trees, 

 and these are of no espe- 

 cial value, I shall have no 

 further occasion to refer to 

 monocotyledonous plants in 

 the ensuing pages. All of 

 the ligneous or trees with 

 firm wood, belong to the 

 exogens, but in some in- 

 stances, such as the pines, the embryo is provided 

 with more than two cotyledons, and there are from 

 three to ten seed-leaves instead of two, but there are 

 never less than two. As the seedlings grow up into 



Fig. 1.— SEEDLING MAPLE. 



