80 GAMOPETALY, ETC. [CH. 



Another point to be noticed is that not all floral 

 envelopes which have delicate, petal-like segments, or 

 are coloured and corolla-like, are true corollas. For in- 

 stance, the four white spreading organs of the Clematis 

 look like petals ; they are, however, really coloured sepals, 

 the corolla being wanting. Similarly with the purplish- 

 pink, corolla-like perianth of Mezereon ; it is really the 

 calyx-tube. 



There are other means also by which flowers, morpho- 

 logically devoid of a corolla proper, nevertheless display 

 coloured organs which at first sight appear to be petals 

 e.g. the coloured bracts of some exotic Cornels, Euphor- 

 bias, &c. 



Further may be mentioned cases where the corollas of 

 the outer flowers of crowded inflorescences are very different 

 in appearance from those of the inner flowers, e.g. many 

 Compositse, such as the Daisy and Candytuft, the Guelder 

 Rose, &c. (Fig. 141). In the common Carrot the corolla of 

 the central flower in the umbel is purple-brown, whereas 

 that of all the other flowers is white. 



We shall see that the chief functions of the coloured 

 petals is to attract insects; the above facts simply serve to 

 remind us that in Nature the same end is frequently 

 served by various mechanisms or adaptations. 



The corolla is gamopetalous in 



In all these cases, except in the Ericaceae e.g. 

 Vaccinium, Erica, Ling, Loiseleuria, Strawberry-tree, 



