30 CLEISTOGAMOUS FLOWERS. [chaP. 



marvellous variety of contrivances found among 

 flowers, and the light thus thrown upon them, by 

 the consideration of their relations to insects ; but I 

 must now call attention to certain very curious cases, 

 in which the same species has two or more kinds of 

 flowers. Probably in all plants the flowers differ 

 somewhat in size, and in some species there are two 

 distinct classes of flowers, one large, and much visited 

 by insects, the other small, and comparatively neg- 

 lected ; while in others, as, for instance, some of the 

 Violets, these differences are carried much further. The 

 smaller flowers have no scent or honey, the corolla is 

 rudimentary, and, in fact, an ordinary observer would 

 not recognise them as flowers at all. Such " cleisto- 

 gamic " flowers, as they have been termed by Dr. 

 Kuhn, are already known to exist in over fifty genera. 

 Their object probably is to secure, with as little ex- 

 penditure as possible, the continuance of the species 

 in cases when, from unfavourable weather or other 

 causes, insects are absent ; and under such circum- 

 stances, as scent, honey, and colour are of no use, it is 

 an advantage to the plant to be spared from the effort 

 of their production. 



As the type of another class of cases in which two 

 kinds of flowers are produced by the same species 

 (though not on the same stock) we may take our 

 common Cowslips and Primroses. If you examine a 

 number of them, you will find that they fall into two 

 distinct series. In some of the flowers, the pistil is as 

 long as the tube, and the button-shaped stigma (Fig. 

 29, st) is situated at the mouth of the flower ; the 

 stamens {a a) being half-way down the tube; whiie 



