20 INTRODUCTION 



the corolla. In a large proportion of the wild 

 flowers the petals seem to be more or less united 

 to form the corolla, which commonly has lobes, 

 each lobe representing a single petal. 



In the case of many flowers one set of these 

 floral envelopes, as the calyx and corolla are 

 sometimes called, is absent. The botanists gener- 

 ally assume that it is the corolla which is absent 

 and call the part present the calyx. If these so- 

 called sepals look like petals they are said to be 

 petaloid sepals. 



In the case of the Lilies and many related 

 flowers there are three outer sepals and three 

 inner petals which are very similar to one another. 

 The six together are said to form the perianth 

 and any one of them is called a perianth segment. 

 This seems a rather technical term and it is per- 

 haps allowable to call these perianth segments 

 petals. 



Within the circle of the petals in the Buttercup 

 flower there are large numbers of stamens. Each 

 stamen consists of a thread-like filament with a 

 more or less bag-like anther on its end in which 

 is held the powdery pollen. 



Within the circle of the stamens there are sev- 

 eral small pistils. The structure of a typical pistil 

 may l>e w^ell seen in that of a Lily, in wdiich the 

 parts are much more distinct than in the case 

 of the Buttercup. As may be seen in the Lily, a 



