BIOLOGY OF THE FLOWER 



157 



carpels, or their equivalents, came into existence first, and 

 that petals, and perhaps sepals, were derived from them 

 by modification of their parts, as may be seen in double 

 flowers like roses, and in the White Water-Lily (Fig. 105). 

 Very ancient flowers had many stamens and carpels arranged 

 spirally on the axis, but in modern flowers the parts are 

 fewer in number and usually arranged in cycles or whorls. 

 Generally the flowers appear towards the end of a season's 

 activities. In an annual they herald the closing scenes of 

 its life-cycle and provide for the formation of fruits and 

 seeds, which will soon be all that remain to perpetuate the 

 race. In some cases flowers appear early in the season and 



Fig. 105. Stamens of Water-Lily, showing transition 

 from Stamens to Petals. 



before the leaves, as in many trees, and in the Coltsfoot, 

 Wood Anemone, and many other herbs. In the Autumn 

 Crocus, or Meadow Saffron (Colchicum autumnale), on the 

 other hand, the leaves complete their work and die down 

 before the flowers appear. Whether early or late, however, 

 the chief object of the flower is to produce fruits containing 

 seeds, which, on falling to the ground, may produce a new 

 generation ; and all the parts of a flowerdirectly or indirectly 

 serve this end. 



Structure and functions of the parts of a flower. The four 

 parts of a typical flower are usually arranged in successive 

 whorls on the short axis, which is known as the receptacle. 

 The lowest and outermost is composed of small green sepals 



