340 A TEXTBOOK OF BOTANY [Ch. VI, 12 



pollinate the clusters in precisely the same way as they do 

 single flowers. These heads in the Compositae represent 

 the highest ev<jlutionary development of clusters. 



12. Special Forms, Abnormalities, and JMonstrosities 

 OF Flowers 



Although leaves, stems, and roots often perform fimctions 

 and have forms very different from those which are pri- 

 mary and typical in those organs, flowers have hardly any 

 additional or substitute functions, doubtless because of 

 their high degree of specialization to their primaiy function. 

 On the other hand, flowers far surpass all other organs in 

 the abundance of their abnormalities and monstrosities, 

 presumably because their much greater complication of 

 structure allows more opportunitj' therefor. 



Abnormal or monstrous flowers, those which deviate in some 

 unusual or eccentric way from the conditions usual in that 

 kind, are apt to occur in any JDed, especially in gardens, — 

 for they are more frequent under cultivation. 



The monstrosities occur in all pos.sible parts. Sepals are 

 found, either singi}^ or the whole whorl, entirely leaf-like in 

 size and appearance, even to complete compounding in 

 some Ptoses. Also they occur so petal-like in color and form 

 as to reseniljle a seemingly two-storied flower, as in ' ' Hose in 

 hose" Primroses. Petals act in many strange ways, even 

 turning leaf-green in some monstrous Roses. They are 

 especially prone to nudtiply much in num]:)er, giving us 

 double flowers, of which a great many kinds can l)e propagated, 

 and occur in our gardens. Stamens are sometimes completeh' 

 petal-like ; sometimes bear ovules in their anthers instead 

 of pollen ; sometimes are completely replaced bj- carpels. 

 Carpels often fail to unite their edges, thus leaving the ovary 

 open ; and they become in vaiious degrees leaf-like. Some- 

 times the ovary contains anthers with pollen instead of 

 ovules, and sometimes the ovules ai-e rejilaced by tiny 

 green leaves. The receptacle also acts diversely, its most 



