I04 Flowers and their Unbidden Guests. 



laria glochidiata, tlie flower of whicli is shown in 

 longitudinal section in Plate III. fig. 87, numerous 

 stamens emerge from the upper margin of the tuhular 

 and nectariferous portion of the flower. The filaments 

 of these stamens lie closely packed together, whorl upon, 

 whorl, and half way up bend inwards in a body so as 

 to form a regular dome, which allows the style to pass 

 through its centre, but elsewhere can only be pene- 

 trated with difi&culty. A similar formation may be 

 seen in Potentilla micrantha Earn., the flower of which 

 plant is represented in Plate III. fig. 90 in longitudinal 

 section. The filaments, however, which are given off 

 from the upper margin of the basin-shaped nectariferous 

 space form in this case only a single row ; they run 

 moreover in a straight line, and are in close contact 

 laterally. The stigmas also do not project above the 

 dome formed by the filaments, and the closure of the 

 opening above is effected by the closely packed anthers. 

 This occlusion of the nectar-cavity by the crowding 

 together of the stamens is brought about in a very 

 peculiar manner in the white ranunculuses of the Alps. 

 . I select as an example Ranunculus glacialis (Plate I. 

 fig. 21, longitudinal section of the whole flower; fig. 

 22, a single petal seen from above ; fig. 23, a longi- 

 tudinal section of such a petal seen from the side). 

 The nectar is here secreted in a little pit on the upper 

 surface of the petals, just above the point where the 

 roundish lamina passes into the tolerably thick claw. 



