138 PULMONARIA. [CHAP. 



different to that in Echium, but, as Sprengel has 

 pointed out, somewhat resembling that already de- 

 scribed in the Violet. The flowers are drooping, of 

 a beautiful blue, with a white central circle ; dark 

 stamens, combined into a tube, and a pink pistil. The 

 pale yellow, fleshy ovary secretes honey, which lies 

 in a short tube formed of the basis of the stamens. 

 The anthers are long, and open gradually from the 

 apex to the base, so that the pollen falls into the 

 closed space between them and the pistil. This 

 arrangement effectually protects both the pollen and 

 the honey from all insects, excepting bees. The 

 latter, however, force their proboscis down to the 

 honey, between the anthers, which, however, return 

 to their former position again, as soon as the pro- 

 boscis is withdrawn. As soon as the anthers are 

 separated, the pollen drops down on to the head of 

 the bee, and is thus carried from one flower to 

 another. Cross-fertilisation is also favoured by the 

 flower being proterandrous, the stigma not becoming 

 mature until the anthers have shed all their pollen. 

 The Borage is much visited by bees, especially by 

 the common hive bee. 



Pulmonaria officinalis (Fig. 96) is a dimorphous 

 species ; being rich in honey and much visited by in- 

 sects, it has not only lost the power of self-fertilisation, 

 but is said by Hildebrand (Bot. Zeit., 1865) to be 

 sterile to pollen from the same form of flower ; that 

 is to say, long-styled flowers require to be fertilised 

 by pollen from short-styled flowers, and vice versa. 

 Darwin, however, succeeded in obtaining seeds and 

 raising seedlings from some long-styled plants which 



