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THE BOOK OF NATURE STUDY 



erect shoots. These have elongated internodes, and at each 

 node a pair of small, oval, foliage leaves with short stalks. The 

 pairs of leaves alternate at successive nodes. On the horizontal 

 shoots the leaves become twisted round so as to spread out in 

 one plane, and appear as if they formed only two rows. From 



the persistent lower 

 portions of the erect 

 shoots lateral branches 

 arise in succeeding 

 years, giving rise to 

 the clusters of erect 

 shoots which spring 

 at intervals from the 

 creeping stems (Fig. 

 67). From these 

 nodes numerous roots 

 grow down into the 

 soil. This mode of 

 growth enables the 

 plant to spread, and 

 is largely responsible 

 for its abundance and 

 success in favourable 

 situations. 



The flowers are 

 borne singly in the 

 axils of one or more 

 of the upper leaves of 

 the erect shoots. The 



FIG. 67. The Lesser Periwinkle. (After Baillon.) 



shoot in the Lesser 

 Periwinkle often has 

 only one flower. This is borne on a slender green stalk, and 

 consists of sepals, petals, and stamens in regularly alternating 

 whorls of five, and of a pistil composed of two carpels. The 

 construction of the flower is a complicated one, and should 

 be carefully studied in several examples, since even the most 

 minute features will be found to have their use in the pollination 

 of the flower by means of insects. 



