TBE FLOWER 



111 



154. FlowiT of the Vinlct ; 

 bfjlow, tli(i i)arls nT 

 the perianth sepa- 

 rated. 



are of unequal size : sucli corollas, and all in which the 



petals art! not entirely uniform, are 



irregular. 



211. A second important respect in 

 which corollas differ is in the sepa- 

 ration or union of the petals. Tlie 

 trumpet-shaped corolla of the Morn- 

 ing Glory (Fig. 155) furnishes an 

 extreme instance of union, where the 

 original petals are 

 not easily distin- 

 guishable. Fre- 

 quently the limb, 

 or border, is so 

 lobed tliat the 



numljer of component parts is evident. 

 Another fatniliar form is the two- 

 lip])eil, lahl<(t<\ ccirolla (Fig- 169). 



212. l\i ease the petals remain quite 

 separate, the corolla is said to be jjolij- 

 petalous ; but if tliey grow U[) luiited when the floral 

 organs are in process of formation, the corolla becomes 

 ffamopetalous. AVhen the petals are all wanting, the 

 flower is apetalous. 



213. The calyx presents features very similar to tlie 

 corolla as regards union of sepals and other modifications. 

 It is usually inferior to the corolla in size and coloration, 

 since its service is chiefly to protect the bud, of whicli it 

 forms the coat. But in numerous plants the calyx shares 

 witli the corolla in anfither duty. 



214. Functions of the perianth. — Tlie role of the perianth 

 in the natural liistory of tlie flower is chiefly twofold : 

 (1) it protects the developing organs within while the bud 

 is coming to maturity ; and (2) at the time of blooming 

 it aids iu the proper distribution of the pollen. Without 

 anticipating the subject of fertilization, it may he said that 

 it is of advantage to plants to secure the dusting of the 

 stigma of each flower l)y the pollen of some other flower of 



15.5. Calyx and corolla 

 of Moruiag Glory. 



