" VlOLACEyE 97 



V. lutea it is short and accessible to flies. In addi- 

 tion to the coloured flowers, some species, for instance, 

 V. canina and T". hirta, produce others (Fig. 61, a, b; 

 see also Fig. 62, a, b) which do not open, in which the 

 petals are either absent or very imperfectly developed, 

 and the anthers produce very little pollen. When young 

 these cleistogamous flowers resemble the ordinary buds, 

 the central part of the flower being entirely covered by 

 the sepals. They set seed abundantly, much more, it 

 is" said, than the coloured flowers. 



V. canina. — The stock is at first short, gradually 

 lengthening. Fig. 58 (l) represents a flower cut in half. 



Fig. 59. — Viola canina. Capsule Fig. 60. — Viola canina. Capsule after 



with seed. ejecting the seeds. 



and Fig. 58 (:2) a stamen. It is visited mainly by bees, but 

 also by a few butterflies and one or two pollen-eating 

 beetles. The stamens consist of a short filament, to 

 which the anther is attached, and a terminal membran- 

 ous expansion, while the two lower stamens also send 

 out each a long spur (Fig. 58, n), which lies within the 

 spur of the median petal and secretes honey at its fleshy 

 end. The terminal membranous expansions of the five 

 stamens slightly overlap one another, and their points 

 touch the pistil, so that they enclose a hollow space. The 

 pollen differs from that of most insect-fertilised flowers 

 in being drier and more easily detached from the 

 anthers ; consequently, when the latter opens the pollen 

 drops out ; and as the flower is reversed and hangs down, 

 the pollen falls into the closed space between the pistil 

 and the membranous termination of the stamens. The 



H 



