BY DR. M. B. BORKHAUSEN. 225 



boundaries. In both the single cauline leaf is 

 sometimes perfectly formed and distinctly petiolated; 

 sometimes it appears stopped in its growth, and 

 often more resembles a stipule than a leaf. The 

 radical leaves are sometimes, in one and the same 

 plant, nearly orbicular or oval, sometimes they are 

 perfectly entire, sometimes rather undulated at the 

 margin, not seldom obsoletely, but as often dis- 

 tinctly and sometimes deeply toothed. This cir- 

 cumstance, as well as the greater or less pubes- 

 cence, is merely owing to the greater or less 

 sterility of the soil. Those leaves which are entirely 

 without teeth, are the most hairy of all, and the 

 deeper they are toothed, the more they lose in 

 hairiness. This hairiness is also different at the 

 different ages of the plant. The young leaf, 

 which has not yet arrived at maturity, is the most 

 hairy, but in proportion as it grows, the pubes- 

 cence becomes gradually thinner, and at last disap- 

 pears entirely. Mr. Schrank thinks he has found 

 a constant character for his Hieracium pilosissimum 

 in the persisting wool of the leaf-stalks ; but accor- 

 • ding to what I have observed, this character is as 



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