106 INFLORESCENCE. 



be opened, is borne upon a peduncle of two or more nodes, which are, of course, 

 transverse to each other (219, c). Prom one, or two, or all of these nodes, pairs 

 of secondary, opposite peduncles arise, each of which, like the first, is binodal or 

 multinodal, and terminated by a flower. Again, in the nodes of these secondary 

 peduncles, may arise, in the same manner as before, pairs of tertiary peduncles, 

 each to be terminated by a flower, and perhaps to bear still other peduncles, and 

 so on. 



b. Hence it is evident, that in each axil of the forked branches there should be 

 a solitary flower. This, however, is often wanting. Irregularities may also be 

 occasioned by the absence of other parts. 



308. FASCICLE. This is a modification of the cyme, in which 

 the flowers become crowded, and nearly sessile, as in sweet 

 william, and other species of Dianthus. 



309. VERTICILLASTER or VERTICIL, called also, though improp- 

 erly, whorl, is a term denoting those reduced cymes which are 

 peculiar to the Labiatse, where two such cymes occupy the 

 opposite axils of each pair of leaves. 



a. Sometimes the peduncle, instead of producing flowers, is changed into a ten- 

 dril, as in the vine. 



CHAPTER XIV. 



REVIEW OF THE PRINCIPLES OF NUTRITION. 



310. It has already been shown, in the preceding chapters, 

 that plants consist chiefly of four simple organic elements ; viz. 

 carbon, oxygen, hydrogen, and nitrogen. The first mentioned 

 exists in a larger proportion, the last in a smaller, than either of 

 the others. These four elements constitute about 94 per cent 

 of all vegetable matter. 



311. CARBON (essentially charcoal) enters so largely into the 

 composition of plants, that it retains the exact form and texture 

 of the wood after the other ingredients have been expelled by 

 heat. On this element chiefly depends their solidity and 

 strength. Its proportion is from 40 to 60 per cent. NITROGEN, 

 although perhaps equally essential, is less abundant in the 

 tissues, and exists largely only in certain important vegetable 

 products ; as gluten, legumine, albumen. 



