314 CLEISTOGAMIC FLOWERS. Chap. Vnfi 



The first point that strikes us in considering this list 

 of 55 genera, is that they are very widely distributed 

 in the vegetable series. They are more common in the 

 family of the Leguminosse than in any other, and next 

 in order in that of the Acanthacese and Malpighiacese. 

 A large number, but not all the species, of certain 

 genera, as of Oxalis and Viola, bear cleistogamic as 

 well as ordinary flowers. A second point which de- 

 serves notice is that a considerable proportion of the 

 genera produce more or less irregular flowers ; this is 

 the case with about 32 out of the 55 genera, but to this 

 subject I shall recur. 



I formerly made many observations on cleistogamic 

 flowers, but only a few of them are worth giving, since 

 the appearance of an admirable paper by Hugo von 

 Mohl,* whose examination was in some respects much 

 more complete than mine. His paper includes also an 

 interesting history of our knowledge on the subject. 



Viola canina. — The calyx of the cleistogamic flowers 

 differs in no respect from that of the perfect ones. The 

 petals are reduced to five minute scales ; the lower one, 

 which represents the lower lip, is considerably larger 

 than the others, but with no trace of the spur-like 

 nectary ; its margins are smooth, whilst those of the 

 other four scale-like petals are papillose; D. Muller of 

 Upsala says that in the specimens which he observed 

 the petals were completely aborted.f The stamens are 

 very small, and only the two lower ones are provided 

 with anthers, which do not cohere together as in the 

 perfect flowers. The anthers are minute, with the two 

 cells or loculi remarkably distinct ; they contain very 

 little pollen in comparison with those of the perfect 



» 'But. Zeitung,' 1863, p. 309- paper contains the first Ml and 

 28. patisfaotory account of any cleisto- 



t Ibid. 1857, p. 730. This gamie flower. 



