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STRUCTURAL AND PHYSIOLOGICAL BOTANY. 



tension, there is no more certain limit to the life of an 

 Endogenous than of an Exogenous tree. 



146. Generally, the terminal bud only of Endogenous plants 

 is developed ; but very often a considerable number develope ; 

 Ex. Asparagus. 



147. When a terminal bud only of an Endogenous plant 

 developes, the stem is cylindrical ; Ex. Palms : when several 

 develope, it becomes conical ; Ex. Bamboo. 



148. In Acrogens no other stem is formed than what arises 

 from the simple union between the bases of the leaves and the 

 original axis of the bud from which they spring, and which 

 they carry up along with them. 



149. In the order of Ferns the section of a stem indicates 

 the same structure as that of the numerous petioles (197) out 

 of which it is constituted. 



150. When Acrogens have no proper leaves, they are mere 

 expansions of cellular matter, sometimes in all directions ; Ex. 

 Fungi : sometimes in particular directions ; Ex. Lichens, 

 Algse, &c. 



151. The stem of a plant assumes numerous and very differ- 

 ent appearances in different plants. 



If above ground it is rootshaped, or knotted 67 ; ascending 68 ; creeping 72 ; arti- 

 culated 73 ; leafless, succulent, and deformed 69 ; or leafy 71 . 



If it bears the fmcers, proceeding immediately from the soil or near it, it is a 

 scape 70 . 



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