THE STEUCTURE OF FLOWERS. 



The next matt^ for consideration is to discover how 

 differences can arise in the structure of flowers. 

 These may be grouped under the following headings : 

 iSTumber, Cohesion, Adhesion, Insertion, and Form. 



Number. — With regard to the number of parts in 

 each whorl, they may vary from one to twelve — all such 

 numbers are said to be definite (see Figs. 6, 7, 8, 12) ; 

 but if there are more than twelve, sometimes very many, 

 such are regarded as being indefinite (Fig. 9, stamens 

 many ; Fig. 10, petals and stamens many), and is repre- 

 sented by the mathematical symbol for infinity, oo . 

 Some numbers are commoner than others, as fives and 

 threes ; fours are less common, and twos are rare. 

 The multiples of these occur, so that there may be 

 eight, ten, or twelve in a whorl. 



Any one, two, or more whorls may be wanting 

 altogether ; so that a flower may be reduced to stamens 

 (Figs. 6, 1. ; 8), or a pistil only (Figs. 5, 11. ; 6, XL). On 

 the other hand, the calyx and corolla may exist without 

 the stamens or pistil. Such a flower is then said to be 

 neuter, as of the garden Hydrangeas. 



