BIOLOGY OF THE FLOWER 171 



In the Apple (Fig. 116) and Pear the pistil consists of 

 five carpels, which are syncarpous and closely united to 

 the hollow receptacle ; the five sepals, five petals, and 

 numerous stamens are thus carried on to the top of the 

 ovary (i.e. the flowers are epigynous). Owing to the 

 union of the five carpels with the receptacle-cup the honey 

 is easily obtained, and the flowers are visited by a great 

 variety of insects. The five stigmas are prominent, ripen 

 before the anthers, i. e. they are proterogynous (Gk. proteros 

 = before), and so favour cross-pollination. If insect-visits 

 fail, pollen may be shaken or may fall on to the stigmas ; this 

 is aided by the horizontal position of the flowers. After 

 fertilization the receptacle enlarges and forms the fleshy 

 part of the fruit. The five united carpels form the core 



(Fig- I5S). 

 Examine old fertilized flowers of the Strawberry, Rose. 



Cherry, and Apple, and note in each case the mode of origin 



of the fruit and the structures concerned in their formation. 



Tubular flowers with concealed honey. Devices to secure 

 cross-pollination. In the Stock (Fig. 3, 1) the four upright 

 sepals form a narrow but split tube, which conceals the 

 nectaries found at the base of the two short stamens. 

 The stamens here, unlike those of the previous flowers, are 

 reduced to six. Such a deepened flower-tube will prevent 

 the short-tongued insects from securing the honey, but this 

 can easily be obtained by the long-tongued insects, such 

 as moths, butterflies, and bees. These insects are more 

 intelligent and better adapted for carrying pollen from 

 anther to stigma than the short-tongued insects, like beetles 

 and flies, which may take pollen and honey from shallower 

 flowers with less likelihood of bringing about pollination. 



Those flowers, therefore, which attract the more intelli- 

 gent insects possess a double advantage : (1) they need 

 less pollen, and (2) cross-pollination is more certain. Let 

 us see by what means these advantages are secured in 

 some other flowers. 



