CHAP IX. SELF-STERILE PLANTS. 335 



hemisphere, with a complete reversal of the seasons, 

 were thus rendered slightly self-fertile, whereas they 

 seem always to be completely self-sterile in their 

 native home. 



Senecio cruentus (greenhouse varieties, commonly 

 called Cinerarias, probably derived from several fruticose 

 or herbaceous species much intercrossed*). Two purple- 

 flowered varieties were placed under a net in the 

 greenhouse, and four corymbs on each were re- 

 peatedly brushed with flowers from the other plant, 

 so that their stigmas were well covered with each 

 other's pollen. Two of the eight corymbs thus treated 

 produced very few seeds, but the other six produced 

 on an average 41 3 seeds per corymb, and these ger- 

 minated well. The stigmas on four other corymbs on 

 both plants were well smeared with pollen from the 

 flowers on their own corymbs; these eight corymbs 

 produced altogether ten extremely poor seeds, which 

 proved incapable of germinating. I examined many 

 flowers on both plants, and found the stigmas sponta- 

 neously covered with pollen ; but they produced not a 

 single seed. These plants were afterwards left un- 

 covered in the same house where many other Cinerarias 

 were in flower ; and the flowers were frequently visited 

 by bees. They then produced plenty of seed, but one 

 of the two plants less than the other, as this species 

 shows some tendency to be dioecious. 



The trial was repeated on another variety with 

 white petals tipped with red. Many stigmas on two 

 corymbs were covered with pollen from the foregoing 

 purple variety, and these produced eleven and twenty- 



* I am much obliged to Mr. lieves that Senecio cruentus, tw- 



Moore and to Mr. Thiselton Dyer silaginis, and perhaps heritieri, 



for giving me information with maderensis and populifoUus have 



respect to the varieties on which all been more or less blended to- 



I experimented. Mr. Moore be- gether in our Cinerarias. 





