THE FLOWER. 25 



halation of oxygen. In tlieir green cells— and in other green parts of 

 plants — are carried on the functions of digestion and assimilation and the 

 manufacture of the nnillitude of principles Avhicli give to plants their 

 peculiar properties. Wherever these principles may be stoi'ed up, whether 

 in the roots, the sten), the bark, the fruit, or in the leaves themselves, 

 they ai'e the product of the green cells, which attain tlieir greatest develop- 

 ment in the expanded leaves. 



THE FLOWER. 



Having studied the organs hy which plants develop and exist as individ- 

 uals, we have next to considfU' those engaged in the process of reproduction. 



At a.' established period in <!very llowering plant's life, the terminal or 

 axillary buds cease to produce leaves, their leaflets undergoing a transfor- 

 mation by which they become reproductive orgais. A bud in this trans- 

 formed condition is termed a flower-bud, and when fully expanded be- 

 comes a flower. 



We have iih-eady seen that leiif-l)u<ls are )iot scattered hap-liazard along 

 the stem, but are arrangfid in a iix.ed, determinate manner ; now, as Jlower- 

 buds are but transformed leaf-buds, we ai'e prepared to find them also oc- 

 cupying fixed positions. This arrangement of flowers is termed inflo- 

 rescence, and demands a brief examination before jiroceeding to the 

 consideration of the structure oi the flower. 



In some plants only the buds terminating the main stem and branches 

 are transformed into flowers ; in others, only the axillary ; in others still, 

 but much more rarely, the flowers are both axillary and terminal. 



When the flowers are all terminal the infloresct ace is termed deter ■ 

 mir^ate; wlien they are all axillary it is termed Indeterminate, because 

 so long as the terminal bud continues to produce leaves with buds in their 

 axils, flowers follow as a matter of course, and their nuniljer is indefinite. 



The organs of inflorescence ai'o bracts, peduncle, pedicel, and 

 receptacle. 



B racts are altered leaves from the axils of which the floral axes spring ; 

 they may be foliaceous, membranous, scarious, or petaloid (colored). Sec- 

 ondary bracts — that is, those at the base of secondary divisions of a floral 

 axis — are termed bractlets. 



A peduncle is a branch directly terminated by a flower ; and its ex- 

 tremity, ixsually more or less enlarged, upon which the floral organs projier 

 are seated, is the receptacle. 



A pedicel is a secondary pednncle, or in other words, the stalk npon 

 which an individual flower of a branching inflorescence is situated. 



Indeterminate inflorescence presents five well-marked forms, 

 termed the raceme, corymb, umbel, spike, and head, each of which 

 is subject to various modifications. 



