382 



ANGIOSPERMAE—DICOTYLEDONES 



stamens. In some species, according to Kerner ('Nat. Hist. PI.,' Eng. Ed. i, II, 

 p. 326), geitonogamy takes place. For though the direction of the style and the 

 position of the stigma remain unchanged the filaments elongate, and curve in such 

 a way that the pollen can reach the stigmas of neighbouring flowers. 



916. S. sorbifolia L. (Herm. Miiller, 'Fertilisation,' pp. 224-6.) — This 

 Siberian species, cultivated in our parks and gardens as an ornamental shrub, attracts 



Fig. 121. Spiraea sorbifolia, L. (after Herm. Miiller). (i) Flower immedialely after 

 opening. (2) Older flower, with some of the stamens dehisced. a, dehisced anthers; 



St, stigma ; w, nectary. 



numerous insects by its large fragrant inflorescences, and because of its richness in 

 nectar and pollen. Hermann Miiller says that the flowers are distinctly protogynous, 

 and that even in the bud the broad capitate stigmas are provided with papillae and 

 project beyond the stamens, which are bent inwards towards one another. When 

 the flower opens the stamens gradually become erect, and successively dehisce from 

 without inwards. Insects therefore effect crossing at the beginning of anthesis ; later 



