ifH THE REPRODUCTIVE ORGANS 



of flowers to determine the chief devices for securing pol- 

 lination and the part played by insects in bringing it about. 



Pollen- flowers : simple forms visited by insects for pollen. 

 The Clematis or Traveller's Joy (Fig. 109) has a calyx 

 consisting of four greenish-white sepals which resemble 

 petals, hence said to be petaloid. There is no corolla ; 

 the stamens are numerous and arranged below the pistil, 

 not in whorls, but spirally. The pistil consists of many 

 carpels which are free from one another, and are hence 

 said to be apocarpous (Gr. apo = from). The flowers 

 secrete no honey, though they provide much pollen for 

 their insect visitors. 



In the Wood Anemone (Fig. no) the flowers appear 

 before the leaves ; but below the flower is a whorl of three 

 large green, leafy bracts. The calyx consists of five peta- 

 loid sepals which are pinkish-white and conspicuous, and 

 act as petals, the corolla being absent. The stamens 

 are numerous (indefinite), and arranged spirally below the 

 pistil, which consists of many small, spirally arranged 

 carpels, free from one another. Examine flowers of different 

 ages, and notice the order of ripening of the stamens and 

 carpels. The outer stamens open first, the stigmas being 

 covered by the inner ones. There is no honey in the flower, 

 but it is visited for pollen by insects which alight in the 

 centre, carry pollen from the anthers on to the ripe stigmas 

 of an older flower, and so bring about cross-pollination. 

 Later, the younger stamens and the stigmas are ripe together, 

 and self-pollination may occur. 



The Marsh Marigold (Fig. in) is a similar flower with 

 a large attractive calyx of five or more yellow sepals. The 

 stamens are numerous and open outwards ; the carpels are 

 free, and each contains several ovules. On the sides of each 

 carpel and near the base are two shallow depressions where 

 honey is secreted. This is an additional attraction for 

 insects. Notice the curious stipule (st), which is quite 



