SPRING FLOWERS 



137 



surface of the cylindrical expansion of the style. The sloping 

 surface formed by these hairs lies immediately within the circle 

 of anthers. The actual receptive surface or stigma is not at the 

 tip of the style, but is the vertical edge or outer surface of the 

 disc-like widening of the latter. The relative positions of the 

 regions of the stamens and style are constant, and will be better 

 understood from a study of the flower with 

 the help of Fig. 68 than by any further descrip- 

 tion. The lower portions of the filaments bear 

 downwardly directed hairs, and, as was seen 

 on looking into the flower, the space between 

 the stamens and the corolla - tube is filled up 

 with similar hairs springing from the corolla. 

 The latter hairs are omitted in Fig. 68. 



The ovary consists of two carpels, which 

 are separate from one another in the lower 

 region of the pistil but joined to form the 

 style. Each carpel in the ovary encloses a 

 cavity which has two rows of ovules springing 

 from the infolded inner margin. Seen from 

 the outside, the ovary has the appearance 

 of a deeply two-lobed, flattened, green body. 

 Alternating with the lobes are two yellowish 

 green glands, not much behind the carpels in 

 size. These are the nectaries, and the nectar 

 formed by them accumulates around the ovary 

 in the lower part of the corolla tube. 



If this very complex inter-relation of the 

 parts enclosed by the corolla is considered with 

 regard to the action of the insects visiting the 

 flower it will be found to be intelligible as a 

 very beautiful adaptation for cross-pollination, 

 in search of the honey, and only those with long tongues can reach 

 this. Humble-bees and some smaller bees are the chief visitors 

 to the Lesser Periwinkle, while only bees with still longer tongues 

 and moths can obtain the honey from the larger flowers of Vinca 

 major. The insects alight on the flat, target-like expansion of 

 the corolla, and will pass their tongues down to the nectar. Owing 



FIG. 69. Pistil of the 

 Greater Periwinkle. 

 The nectaries are 

 seen to either side 

 of the ovary. (After 

 Baillon.) 



The insects come 



