LVTHKUM SALICARIA. 



CHAPTER II. 



I NOW pass to the structure and modification of 

 flowers. A complete flower consists of (i) an outer 

 envelope or calyx, sometimes tubular, sometimes con- 

 sisting of separate leaves called sepals ; (2) an inner 

 envelope or corolla, which is generally more or less 

 coloured, and which, like the calyx, is sometimes 

 tubular, sometimes composed of separate leaves, called 

 petals ; (3) of one or more stamens, consisting of a 

 stalk ox filament, and a head or anther, in which the 

 pollen is produced ; and (4) a pistil or an ovary, which 

 is situated in the centre of the flower, and contains 

 one or more seeds or ovules. The pistil consists of a 

 stalk or style ; and a stigma, to which the pollen must 

 find its way in order to fertilize the flower, and which 



