104 HETEROSTYLED DIMORPHIC PLANTS. CHAP. III. 



yield some seed, instead of being absolutely self-sterile 

 like the German plants. 



Pulmonaria angustifolia. Seedlings of this plant, 

 raised from plants growing wild in the Isle of Wight, 

 were named for me by Dr. Hooker. It is so closely 

 allied to the last species, differing chiefly in the shape 

 and spotting of the leaves, that the two have been con- 

 sidered by several eminent botanists for instance, 

 Bentham as mere varieties. But, as we shall presently 

 see, good evidence can be assigned for ranking them 

 as distinct. Owing to the doubts on this head, I tried 

 whether the two would mutually fertilise one another. 

 Twelve short-styled flowers of P. angustifolia were 

 legitimately fertilised with pollen from long-styled 

 plants of P. officinalis (which, as we have just seen, 

 are moderately self -fertile), but they did not produce 

 a single fruit. Thirty-six long-styled flowers of P. 

 angustifolia were also illegitimately fertilised during 

 two seasons with pollen from the long-styled P. 

 officinalis, but all these flowers dropped off unim- 

 pregnated. Had the plants been mere varieties of 

 the same species these illegitimate crosses would 

 probably have yielded some seeds, judging from my 

 success in illegitimately fertilising the long-styled 

 flowers of P. officinalis; and the twelve legitimate 

 crosses, instead of yielding no fruit, would almost cer- 

 tainly have yielded a considerable number, namely, 

 about nine, judging from the results given in the fol- 

 lowing table (20). Therefore P. officinalis and angus- 

 tifolia appear to be good and distinct species, in con- 

 formity with other important functional differences be- 

 tween them, immediately to be described. 



The long-styled and short-styled flowers of P. angus- 

 tifolia differ from one another in structure in nearly 

 the same manner as those of P. officinalis. But in the 



