III.] 



OXALIS. 



which in the meantime has elongated, and assumes the 

 position which the stamens had successively occupied ; 

 the result of which is, that a bee which had pre- 

 viously visited a younger flower and dusted her 

 breast with pollen could not fail to deposit some of 

 the pollen on the stigma. It will be observed that 

 the lines on the flower as usual point to the honey. 

 The three lower petals bear a number of lanceolate 

 processes, which, as Sprengel has pointed out, serve 



r\ 



FIG. 65. Flower of Tropceolum majors the third stage. The anthers have all shed 

 their pollen, and the pistil now occupies the position in front of the entrance to 

 the spur. 



to prevent rain from obtaining access to the tube, 

 and also perhaps in guiding the insects, so as to 

 bring their breasts truly against the anther or stigma. 

 The calyx, which from the position of the flower is 

 almost as much exposed as the corolla, is of the 

 same colour as the petals. 



Oxalis acetosella is one of the species which produces 

 u cleistogamous " flowers (see ante p. 36). This was 

 first, I believe, observed by Michelet (Bull. Soc. Bot. 

 de France, 1860, p. 465). 



G 2 



