DOUBLE FLOWERS 



145 



morphologically: (1) stamensor pistils maycTwngt to petals 

 (Fig. 235); (2) adventitious or accessory petals may arise 

 in tin circle of pet- 

 als. Both of these 

 categories may be 

 present in the same 

 flower, as in Figs. 

 233, 234, and 235. 

 In the full-double 

 hollyhock, the pet- 

 als derived from the 

 stamina] column are 

 shorter and make 

 a rosette in the cen- 

 ter of the flower. 

 Other modifications 

 of flowers are sometimes known as doubling. For ex- 

 ample, double dahlias (Fig. 232), chrysanthemums and 



sunflowers are forms in 

 which the disk flowers have 

 developed ra\ s. The snow- 

 ball is another ease. In the 

 wild plant (Fig. 236) I he ex- 

 ternal flowers of I he cluster 

 are large and sterile. In 

 the cultivated plaid (Fig. 

 237) .-ill the flowers haw be- 

 come Large and sterile. II\ - 



drangea i> a similar case. 



2:!(i. The wild or original form of tin- snowball. 

 Outer flowers larger. 



Review. Bow do flowers 

 vary in fonnf Bow are the var- 

 ious parts determined in disguised 

 flowei - .' Whal b re B merous and 



3-merous flowi is? "Wh.-it :ii-<< s<>ii f tin' <<>iumon Forms of gamo- 



pct ;il< ins coin] l.-is .' 1 )<-s<-ni>n a lniiiiito flower. Pei - ma ' < . Lily flower. 

 Papilionaceous flower. What are monadelphous and diadelphous Bta- 



237, Cultivated snowball, Inwbichall th< 

 flowers in the cluster have becomi 

 large and Bhowj 



