CHAPa II. 
STEM. 
73 
gardens as the Tree Mignionette. The under«shrub is ex- 
actly intermediate between the shrub and the herb. All 
plants producing shoots of annual duration from the surface 
of the earth are called herbs. 
Some botanists distinguish two sorts of stems, the 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 in- 
determinate ; but when a stem has its growth uniformly 
stopped at a particular period of its existence by the production 
of a terminal bud, or by some such cause, it is called deter- 
minate, The capitate and verticillate species of Mint owe their 
differences to causes of this nature ; the stem of the former 
beino^ determinate, the latter indeterminate. 
The point whence two branches diverge is called the axil, 
or, in old botanical language, the ala. 
Leaf- buds [Gemma, Linn.), being the rudiments of young 
branches, are of great importance in regard to the general 
structure of a plant. They consist of scales imbricated over 
17 18 
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 their protection. 
