SPRING FLOWERS 127 



the anther (Fig. 64, B). These extend back into the spur of the 

 anterior petal, which is adapted to contain them (Fig. 64, A) and 

 are the structures which secrete the nectar. This accumulates in 

 the spur. 



The pistil is seen if the stamens are carefully removed. It 

 consists of a small three-sided conical ovary continuing into a 

 slender style, the tip of which bends down in front of the tips 

 of the stamens. This bent tip is the stigma. The ovary is formed 

 of three carpels, but has only a single cavity. The ovules are 

 borne on the inner surface of the wall of the ovary in three rows, 

 which correspond to the lines of union of the carpels (cf. Fig. 56, c). 



If, having studied the form of all the parts of the flower, 

 we take another specimen, and look at it from in front, the 

 relative positions of the parts will be appreciated. The stamens 

 and pistil will be seen to be enclosed by the basal portions of the 

 petals, the tip of the cone formed by the stamens projecting in 

 the opening of the flower. In front of this the style bearing the 

 hooked stigma projects. Entrance to the spur, within which 

 the nectar is contained, might be by the sides or beneath the 

 staminal cone. The passage by the side of this is, however, filled 

 up and blocked by the tufts of hairs projecting inwards from 

 the two lateral petals. It is thus clear that the only easy way 

 into the spur will be beneath the cone of stamens. 



The flowers of the Sweet Violet are visited by a number of 

 different kinds of insects, especially by bees, which come in search 

 of the nectar secreted by the appendages of the two anterior 

 stamens. Pollination is most satisfactorily effected when the 

 insect alights on the anterior petal, and passes its proboscis be- 

 neath the stamens into the spur. In doing this it will touch 

 the stigma first, and will then have pollen deposited on its pro- 

 boscis, either by disturbing the stamens, when pollen will fall 

 out of the box formed by the anthers, or from the groove in the 

 petal, where pollen will have fallen. On the insect going to another 

 flower the pollen on its proboscis will be deposited on the stigma, 

 and the flower will be cross-pollinated. Pollination does not 

 appear to result if the visits of insects are prevented, and the 

 whole construction of the flower indicates its high specialisation 

 for insect pollination. The shape of the irregular flower leading 



