204 



Introduction to Botany. 



i'lG. 122. 



Transition between stamens and petals in 

 NymphcEO. odorata. After Gray. 



more than one, compomid. The sepals and petals may be 

 either modified foliage leaves or barren sporophylls. Evi- 

 dence that they may be 

 the latter is found in the 

 fact that all gradations of 

 transition between sta- 

 mens and petals occur in 

 the sweet-scented pond 

 lily, Ny7npkcea odorata 

 (Fig. 122), and in various 

 double flowers. But on 

 the other hand all de- 

 grees of gradation may be 

 found from foliage leaves, 

 through sepals and petals 

 to stamens, so that along this line of evidence we cannot 

 come to a positive conclusion. Since in the relatively 

 ancient Lycopodiums and Selaginellas there may be no 

 difference in appearance between the foliage leaves and 

 sporophylls, and in others there may be all degrees of 

 gradation between them, it would seem that foliage leaves 

 and sporophylls have had a common origin. 



The relative positions of the different parts of flowers may 

 show considerable variation, as seen in diagrams of row d, 

 A, B, C, D, of Fig. 123. When the parts arise near to- 

 gether on the apex of the receptacle {d, A), the pistil is 

 said to be superior and the flower kypogynous. When the 

 outer part of the receptacle is prolonged into a tube or cup 

 carrying the sepals, petals, and stamens above the in- 

 sertion of the pistil {d, B), the pistil is called half inferior 

 and the flower perigyiious. When the zone of the re- 

 ceptacle bearing sepals, petals, stamens, and carpels is 

 prolonged in the form of a hollow tube or cup which forms 



