II GENTIANACE^ — POLEMONIACE^ 289 



equal length. Knuth, near Kiel, and other observers, 

 found two forms, one long-styled and one short-styled, 

 as in Primula. In England also they are dimorphous. 

 As in Primula, the papillse of the stigma (Figs. 187, 188) 

 and the pollen of the two forms differ in size. The 

 flowers are very little visited by insects — at least by day. 



LiMNANTHEMUM 



Dimorphous flowers, with concealed honey, secreted 

 by five nectaries between the roots of the stamens. 



L. nymphseoides. — This is a floating water plant, well 

 named from its resemblance to a water-lily. Flies are 

 much attracted to the flowers by a sap which exudes 

 from the cells of the corolla. The entrance to the 

 flower-tube is occupied by numerous filaments. The 

 pistil of the long-styled is about one and a half times as 

 long as that of the short-styled form. The bud forms 

 under water, the flower emerges as it opens, and after 

 it fades the stalk turns down again and the seed 

 matures below the surface. This is a most unusual 

 arrangement. When ripe the seed rises ; it is lenticular, 

 the surface is smooth, and not wetted by water, so that 

 it floats and is carried about by currents ; the edge, 

 moreover, bears a row of stiff roughened hairs, which 

 no doubt sometimes attach themselves to animals — 

 perhaps, also, they tend, in conjunction with the lens- 

 like form, to make the seed float. 



POLEMONIACE^ 



POLEMONIUM 



Protandrous flowers, with concealed honey, which is 

 secreted at the base of the ovary. The filaments of the 

 stamens are dilated into hairy scales. 



P. cseruleum. — A glabrous or slightly pubescent 

 plant, the flowers of which are united in a beautiful 

 terminal corymb or panicle. The access to the honey 



V 



