1730 A TEXTBOOK OF THEORETICAL BOTANY 



our example the common rock-garden Pink, Dianthus deltoides, the Maiden 

 Pink. 



The flowers (Fig. 1606) are protandrous and usually large and brightly 

 coloured. The claws of the petals are long and winged and are held together 

 so as to form a tube by the tubular calyx, which is itself generally sur- 

 rounded by tough bracts which may prevent humble bees from attempting 



Fig. 1606. — Dianthus deltoides. A, Outer stamens elongating. B, Styles 



elongating. 



to reach the nectar by biting through the calyx. The nectar is concealed 

 at the bottom of the corolla tube, which is so long and narrow that as a rule 

 only the long tongues of butterflies can reach the bottom. The stamens 

 and petals spring from a ridge of the receptacle which surrounds the base 

 of the ovary. On the inner edge of this ridge is a yellow fleshy cushion 

 which secretes the nectar. At the beginning of anthesis, the tubular 

 passage formed by the corolla is made so narrow by the presence of the 

 five inner stamens which it encloses, that only the fine proboscis of the 

 insect can reach down it. The path to the nectar is indicated by nectar 

 guides in the form of whitish spots on the rose-red petals. The five outer 

 stamens elongate first, so that their anthers project out of the corolla tube 

 when they dehisce, and after they have withered the inner five stamens 

 elongate in a similar way. At all times the entrance to the tube is covered 

 by the anthers so that the probing insect is sure to receive pollen on its 

 head. When all the pollen has been shed the two styles, which up to now 

 have remained twisted together in the corolla tube, elongate and their 



