LECT. VII.] ANATOMY OF STEMS. 305 



" simple fasces of petioles, or leaf-stalks * ;" al- 

 though circumstances occasion these to unite in 

 the interior of the stipe, and form masses of com- 

 pact wood. This variety of stipe does not increase 

 in diameter. 



The Aloes, the Yucas, and the Dracaena differ 

 in their mode of growth from the Palms, inas- 

 much as they give off branches and increase in 

 the diameter of their stems. From the observa- 

 tions of M. Aubert du Petit-Thouars -f- , who traced 

 the mode of branching, and the consequent in- 

 crease of diameter in the stem of the Dracaena, 

 it appears that the branch originates in a small 

 protuberance under the epidermis, which it soon 

 ruptures ; and extending, first unfolds some scales 

 and then leaves, the result of the successive de- 

 velopment of which is a cylindrical branch com- 

 posed of ligneous cords, similar, in every respect, 

 to the parent stem, and seated upon it like a graft. 

 The ligneous cords, at the point of their junction 

 with the adult stem, spread out at first like rays, 

 and then extend, in an opposite direction to the 

 growth of the branch ; the exterior descending in 

 straight lines towards the earth, whilst the others, 

 after ascending a little at first, soon, also, bend 

 down and take the same course, which the whole 



* ElSmens de Phys. vSget. 1. p. 121 . 



f Essais sur la Vegetation, &c. Paris, 1809, p. 1. 



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