CHAPTER XXI. 



THE DEVELOPMENT OF THE FLORAL WHOKLS. 



The order in which the several whorls of flowers emerge 

 from the axis is, as stated above, almost invariable ; but the 

 rates of development are very various, and important sexual 

 and other differences follow as the results. For flowers with 

 conspicuous corollas or other structures attractive to insects, 

 the prevailing order of progression subsequent to emergence 

 is first the calyx, secondly the stamens, and, if tbere be two 

 series, the whorl superposed to the sepals grows first, 

 afterwards the whorl superposed to the petals ; then follows 

 the pistil to a point approaching maturity, when the corolla, 

 just before expansion, grows very rapidly to its full size ; and 

 finally the stigmas mature. The anthers have also grown 

 long before the filaments, which at last elongate very rapidly. 

 The usual result on maturity is various degrees of jirotandry, 

 coupled with conspicuousness or attractiveness to insects. 

 As a few of the examples I have examined may be mentioned 

 Hanuncnlus acris, Cardamiiie pratensis, Sfellaria Holostea, 

 Lychnis dioica (male), Malva moschata, Geranium (larger 

 flowered sp.). Pelargonium, Tropceohim,, Epilohium hirsutum, 

 (Enotliera biennis, Ipomcea, Veronica Ghamcedrys, etc. In fact, 

 this order of growth and development prevails generally with 

 flowers having conspicuous coi'ollas. 



The interpretation appears to be as follows. In such 



