THE ANGIOSPERMAE 



1237 



the over-arching anthers. The style then elongates and the marginal hairs 

 on the flaps sweep out the last of the pollen from the anthers. The flaps then 

 close and the style bends downwards. In this position contact with the back 

 of a visiting insect may squeeze out some pollen, but later the stigma itself 



Fig. 1 193. — "Pollen chamber" in Goodeniaceae. A, Scaevola. Flower 

 with corolla remo\ed to show anthers dropping pollen into the stigmatic 

 cup. B, The same, stigmatic cup in section at a later stage, the growth 

 of the stigma pushing the pollen out. C, Selliera. Stigmatic cup in 

 section, containing pollen from the same flower. Growth of stigma 

 beginning. {Partly after Goebel.) 



elongates and pushes out the remainder of the pollen from the chamber, 

 from which the stigma now protrudes. Finally the stigma itself becomes 

 receptive and self-pollination is practically excluded. Analogous methods 

 of pollen collecting are to be found in several other families, for instance, 

 Proteaceae, Marantaceae and Polygalaceae, some portion of the style 

 collecting pollen from the anthers and holding it for removal by insect 

 visitors before the stigma ripens. A noteworthy feature of these specialized 

 methods of pollen presentation is that they are in many cases associated with 

 comparatively sparse production of pollen and hence with a need tor 

 economy in its use. 



Tubular styles, such as those of Viola, are hollow compound structures 

 with a tubular opening and without any receptive stigma but with the 

 interior filled with a mucous excretion from the lining membrane. The 

 style has a sharp elbow-bend near its base, with a narrowed lumen, and at 

 its apex is also bent downwards at right angles, ending in an opening which 

 may be formed by one of the three component stigmas. When the style is 

 pressed by an insect it bends easily at the elbow, closing the lumen. The 



