THALAMIFLOR.E 135 



yellow, and lie on the outer side of the outer stamens 

 with a honey-secreting pit above. The flow^ers 

 develop in three stages, the outer stamens first, then 

 the inner lying round the centre of the flower and 

 turning their pollen-covered anthers upwards. In 

 the first stage the three stigmas are bent inwards, in 

 the second they are erect, with the papillae turned 

 towards each other, and in the third they turn out- 

 wards, so that cross-pollination is most likely if 

 insects visit the flowers, though self-pollination may 

 occur by the stigmas touching the inner anthers 

 (still pollen-covered), if insects do not come to the 

 flowers. 



The capsule opens above, being a '' censer fruit," 

 and the seeds are dispersed by the wind, when the 

 stalk is agitated by it, or by passing animals. 



Cerastium arvense. — The habit of the /lower is 

 well illustrated in Fig. 24, and the calyx is seen to be less 

 than the corolla, with notched petals. The essential parts 

 of the flower are visible in the snb-central flower. 



12. The Water Blinks or Purslane Group. 



In the order Portulacese are included, amongst 

 British plants. Water Blinks and two species of 

 Claytonia. 



There are nearly 150 species and 17 genera, which 

 are of universal distribution, but more characteristic 

 of the American flora. 



The group shows relationship with the Caryophyl- 



