LEAVES. 29 



Entire 126 ; serrate 114 ; biserrate 137 ; dentate 139 ; duplicato-dentate 137 ; tri-den- 

 tate 125 ; crisp or curled 129 ; crenate 120 . 



222. The point of the leaves gives rise to other terms, such 

 as the following : 



Acute 118 ; obtuse 139 ; retuse 113 ; emarginate 113 ; acuminate 119 ; mucronate 132 ; 

 truncate 129 . 



223. STIPULES are attached to each side of the base of the 

 petiole. They have, if leafy, veins, the anatomical structure 

 of which is the same as that of the veins of the leaves. 



224. Sometimes only one stipule is formed, the other being 

 constantly abortive, as in Azara. 



225. Stipules are sometimes transformed into leaves : they 

 sometimes have buds in their axils ; and may be, therefore, 

 considered rudimentary leaves. 



226. Whatever arises from the base of a petiole, or of a 

 leaf, if sessile, occupying the same place, and attached to each 

 side, is considered a stipule. The appearance of this organ is 

 so extremely variable, some being large and leaflike, others 

 being mere rudiments of scales, that botanists are obliged to 

 define it by its position, and not by its organization. 



227. The stipules must not be confounded with cellular 

 marginal appendages of the petiole, as in Apocynacese. 



228. Stipules, the margins of which cohere in such a way 

 that they form a membranous tube sheathing the stem, are 

 called ochreee ; Ex. Rhubarb. 



229. All leaves are originally continuous with the stem^ 

 as they grow, an interruption of their tissue at their junction 

 with the stem takes place, by which a more or less complete 

 articulation is formed sooner or later. 



230. The articulation between a leaf and stem being com- 

 pleted, the tissue of the former becomes gradually incrusted 

 by the foreign matter deposited by the sap in the process of 

 secretion and digestion, and at last is incapable of further 

 action, when -it dies. When the stem continues to increase 

 in diameter, as a dead leaf will not increase with it, the latter 

 is eventually thrown off; this is the fall of the leaf. But in 

 some Endogens the articulation is so slight, and the stem 

 increases so little in diameter, that the leaf is never thrown off, 

 but simply withers and decays. 



