BY DR. M. B. BORKHAUSEN. 227 



there are many modifications and approximations, 

 which make it often very doubtful, whether a plant 

 belong to the one or the other. I observed the 

 stalk — 1. entirely without leaves. 2. with a leaf 

 not grown out and resembling a stipula. 3. with 

 leaf completely grown. 4. with a leaf and a sti- 

 pule. 5. with a broad petiolated leaf, and another 

 narrower and sessile. 6. with two distinct leaves, 

 the lower petiolated, the upper sessile, and another 

 not grown out, and resembling a stipule. 7. with 

 three complete leaves, the lower petiolated, the 

 two upper sessile. In both, when in a young 

 state, I observed the leaves to be hairy, as in 

 Hieracium murorum j which pubescence disap- 

 peared from the upper surface when the plants 

 were on the decline. Should not these obser- 

 vations warrant the inference, that also Hieracium 

 murorum and H. sylvaticum are mere varieties of 

 the same species ? 



f 2 



