BARTSIA. 



147 



The other British genera of this group have narrow 

 tubular flowers ; in which the upper lip protects the 

 anthers and pistil, while the lower lip serves as an 

 alighting stage for insects. The stamens are so ar- 

 ranged that the insects in searching for the honey 

 dust themselves with the pollen. For instance, in 

 Bartsia odontites (Fig. 103), the common red Bartsia, 

 the flower forms a tube 4 5 mm. long ; at the base 

 of which is the honey, while the entrance is protected 

 against rain by the four hairy anthers. These lie 



FIG. 104. Bartsia odontites. 

 with a short pistil. 



Flower 



FIG. 105. Ditto. Flower with a long 

 pistil. 



close together; but immediately below them, the 

 filaments of the stamens separate so as to leave a 

 space through which bees can insert their proboscis, 

 and thus reach the honey. In doing so they natur- 

 ally dust themselves with pollen, some of which 

 they transfer to the stigma (Fig. 105, st) of the 

 next flower they may visit. Miiller has observed 

 that in plants of this species which live in shady 

 places and are consequently less visited by insects, 

 the pistil is shorter (Fig. 104), the stigma consequently 



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