INTRODUCTION. 



XXI 



to mention the principal modifications of the 

 leaf which exist in some one or other of our 

 common flowers. After the expansion of a bud 

 of this more complicate structure, a stem will 

 be observed to protrude very similar to a petiole, 

 except that it is not channelled on its upper side, 

 and is generally known by the name of peduncle. 

 It is either simple or branched, and bears at its 

 extremity, or in the latter case at the extremity 

 of each pedicel (or little peduncle), several small 

 leaves (sepo.ls) united at their bases so as to form 



a cup, hence called the calyx. The modified 

 leaves which constitute the calyx are usually of a 

 different form from the true leaves, but not 

 always ; the sepals of some species 

 of . Rose scarcely differ from the 

 leaves, except in being smaller and 

 more dilated at the base. The 

 calyx is frequently accompanied 

 externally by small stalkless leaves, 

 which are termed bracts. They 

 are generally more like the sepals 

 than the true leaves, but some- 

 times, and especially when continued through the 

 whole length/of the peduncle, pass by an almost 



CALYX LEAF OF 

 ROSE. 



