GEITONOGAMY. 



329 



flowers is more often effected by the wind. This process will be rendered clearer 

 with the help of figs. 295 ^' ^' ^- *- The flowers are arranged in a row, with their 

 mouths directed to one side pointing obliquely downwards (295 '^). Flowering 

 begins at the top of the branch, and then works gradually downwards. The stigma 

 comes into sight simultaneously with the opening of the corolla, and protrudes 

 some distance in front of its mouth by the elongation of the style. The anthers 

 surrounding the style are still closed, and are either wholly or half hidden in the 

 corolla (295 ^). Bees coming to suck the honey at the base of the flower inevitably 



Fig. 295.— Geitonogamy with dust-lilce pollen. 



^ Erica mrma; branch with flowers on one side only. 2 Flower of the same in its first stage, s The same flower in its lasl 

 stage. * Single stamen of Erica camea. s Lathrcea Sqiutmaria; upper part of inflorescence. 6 Front view of a flowei 

 which has just opened. 7 Two anthers with closed loculi from the same flower, s Front view of a flower at a later stage. 

 ^ ^^ 11 longitudinal sections of three flowers in the first, second, and third stages respectively. 12 Xwo anthers whose 

 floury pollen has fallen, leaving empty loculi. 1 and 6 nat. size; the others somewhat enlarged. 



brush against the stigma in consequence of its peculiar position. If they have 

 brought pollen with them from other Heaths, a crossing between different plants is 

 the result. Meanwhile large pores have formed in the anthers (see fig. 295 *). But 

 since the pores on adjacent anthers are in immediate contact with one another, 

 and since the anthers themselves are held together by the corolla (which is rather 

 constricted at its mouth), as if by a ring, the pollen remains stored up in the anther- 

 cavities and the pollen-tetrads do not fall out unless disturbed in some way. The 

 anthers are disturbed whenever a bee inserts its proboscis into the flower in search 

 of the honey, and therefore the same bee which at first brushed against the project- 



