170 LEAF-BUDS GROWING POINT. [BOOK i. 



characters of which are derived from the mode of growth. 

 When a stem is never terminated by a flower-bud, nor has 

 its growth stopped by any other organic cause, as in Veronica 

 arvensis, and all perennial and arborescent plants, it is said 

 to be indeterminate ; but when a stem has its growth uni- 

 formly stopped at a particular period of its existence by the 

 production of a terminal bud, or by some such cause, it is 

 called determinate. The capitate and verticillate species of 

 Mint owe their differences to causes of this nature ; the stem 

 of the former being determinate, the latter indeterminate. 



The point whence two branches diverge is called the axil, 

 or, in old botanical language, the ala : a term now extended 

 to the angles formed between leaves and the branch on which 

 they grow. 



Leaf-buds (Gemmce, Linn.), being the rudiments of young 

 branches, are of great importance in considering the general 

 structure of a plant. They consist of scales imbricated over 



11! 



each other, the outermost being the hardest and thickest, 

 and surrounding a minute cellular axis, or growing point, 

 which is in direct communication with the woody and cellular 

 tissue of the stem. In other words, they may be said to be 

 growing points covered with rudimentary leaves for the 

 purpose of protection, and to consist of a highly excitable 

 mass of cellular substance, originating in, or connected with., 

 the pith, or cellular portion of the branch, and having a 



