11 PORTULACE.-E — HYPERICACEyE 115 



HOLOSTEUM 



H. umbellatum. — The flowers are protandrous. The 

 stamens vary from 2 to 5 — 3 being the usual number. 

 Each has a green fleshy nectary at the base. The 

 flower is visited by flies and bees, but often fertihses 

 itself. The flowers are three to eight in number, forming 

 an umbel. They are on long pedicels, erect when flower- 

 ing, then turned down, but erect again when the seeds 

 are ripe. 



POLYCARPOX 



p. tetraphyllum. — The flowers are very small, and 

 may almost be said to be cleistogamous, as indeed they 

 have been by Wiesner.^ 



POETULACE.E 

 MONTIA 



M. fontana. — The seeds are comparatively large, 

 black, and somewhat shining. The testa is covered with 

 relatively large tubercles, densely arranged in lines 

 following the curvature of the seed. 



Claytonia 



0. perfoliata. — This species also has intensely black 

 orbicular seeds. It is a North American plant which 

 has become naturalised in Britain. 



HYPEEICACE^ 



Hypericum (St. John's Wort) 



This is the only British genus of the family. The 

 c feature is the 1 



Biologie der Pflanzen, 1889. 



most characteristic feature is the large number of 



