FLOWERS, THEIR STRUCTURE AND KINDS 155 



which surrounds the upper part of the style and the stigma. 

 They open by their inner face, shedding the pollen on the hairy 

 outer faces of the stigma. 



257. The pistil. The ovary is narrowly wedge-shaped, four- 

 sided by compression. The style is long and slender, and the 

 stigma is divided longitudinally into two portions. The inner 

 plane surfaces fit closely together, and the outer hairy surfaces 

 are in contact with the anther locules up to and during the 

 early stage of flowering. 



258. Peculiarities in the flowering of the disk flowers. 

 The mode of inflorescence is centripetal as described above, i.e., 

 it proceeds from the outside inward. At the time of flowering 

 the anther tube and the stigma which it surrounds are pushed out 

 of the corolla tube by the gradual elongation of the filaments 

 and the style, though the anthers are often slightly in advance of 



Fig. 115. 



Section through head of sunflower, showing details of flowering from the outside 

 toward the center. 



the stigma (see figs. 114, 115 for details). This takes place, as I 

 have observed it, during the night and early morning. In the 

 course of two to four hours, the style having reached its full 

 length, the filaments shorten and draw the anthers down into 

 the corolla tube again. While this is going on the style remains 

 elongated, and the upright hairs on the outer face of the cleft 

 portion of the style catch the pollen as the open anthers are 

 dragged downward. The great mass of pollen is thus left on the 



