CHAP. VIII. OXALIS. 321 



sometimes one or even two of the others are thus pro- 

 vided. Lastly, in V. canina never more than two of 

 the stamens, as far as I have seen, bear anthers ; the 

 petals are much more reduced than in V. hirta, and 

 according to D. Miiller are sometimes quite absent. 



Oxalis acetosella. The existence of cleistogamic 

 flowers on this plant was discovered by Michalet.* 

 They have been fully described by Von Mohl, and I 

 can add hardly anything to his description. In my 

 specimens the anthers of the five longer stamens were 

 nearly on a level with the stigmas ; whilst the smaller 

 and less plainly bilobed anthers of the five shorter 

 stamens stood considerably below the stigmas, so that 

 their tubes had to travel some way upwards. Ac- 

 cording to Michalet these latter anthers are some- 

 times quite aborted. In one case the tubes, which 

 ended in excessively fine points, were seen by me 

 stretching upwards from the lower anthers towards 

 the stigmas, which they had not as yet reached. My 

 plants grew in pots, and long after the perfect flowers 

 had withered they produced not only cleistogamic but 

 a few minute open flowers, which were in an inter- 

 mediate condition between the two kinds. In one of 

 these the pollen-tubes from the lower anthers had 

 reached the stigmas, though the flower was open. 

 The footstalks of the cleistogamic flowers are much 

 shorter than those of the perfect flowers, and are so 

 much bowed downwards that they tend, according to 

 Von Mohl, to bury themselves in the moss and dead 

 leaves on the ground. Michalet also says that they 

 are often hypogean. In order to ascertain the num- 

 ber of seeds produced by these flowers, I marked eight 

 of them ; two failed, one cast its seed abroad, and the 



Bull. Soc. Bot. do France,' torn. vii. 1860, p 465. 



