204 NOTES ON SOME HIERACIA NEW TO BRITAIN. 



scientific terms useful to conceal our ignorance. He was prepared 

 to accept in the main the views Mr. Clarke had put forward. He 

 said that the old experiment of water rising in cut stems, as when 

 cut flowers revived on being placed in water, showed that water 

 could rise without root-pressure. It was, therefore, not necessary 

 to presume a root-pressure, which involved grave and acknowledged 

 difficulties. 



Prof. Ward, on the other hand, said he could not see his way to 

 do without the hypothesis of root-pressure altogether. He thought 

 Mr. Clarke had not sufficiently estimated the complication of struc- 

 ture in a vegetable stem. He referred to the observed fact, that 

 when stimulus (as warmth) was applied to the roots of a stem 

 (which had been cut across and fitted with a manometer), the pres- 

 sure was observed to increase. 



Mr. Clarke, in reply to Mr. Ward, maintained that the action, 

 so far as it was transmitted mechanically in this case, would 

 be transmitted in accordance with the laws of capillary action, not 

 with the equation p^gpz. He said that, in the case of capillary 

 tubes of any length, or of a system of such tubes of considerable 

 length, a very high pressure would be requisite to force fluid 

 through them. 



NOTES ON SOME HIERACIA NEW TO BRITAIN. 



By Frederick J. Hanbury, F.L.S. 



I purpose making the following notes as brief as possible, and 

 would say at once that they by no means treat of all the new 

 species and forms found by myself and others during the summers 

 of 1885, 1886, and 1887, chiefly in the extreme north. It seemed 

 desirable, however, not to delay their publication any longer, as 

 another collecting-season has come round, and the knowledge of 



what has been 



further 



mi 



Nearly all the 



mane iuriner researcnes m the same direction, neaiiy nu, tu, 

 plants here treated of have been seen by Professor Babington and 

 Mr. Backhouse, and all by Dr. 0. J- Lindeberg, the well-known 

 authority on the Scandinavian Hieracia. These gentlemen have 

 made copious notes and given most valuable opinions on the speci- 

 mens submitted to them. I was accompanied in 1885 by the 

 Rev. H. E. Fox, and in 1886 by the Rev. E. S. Marshall. Though 

 availing myself freely of the kind help afforded me by others, it 

 must be understood that they are in no way collectively responsible 

 for the statements here made. 



The following species, recognised by continental authors have 



not hitherto been recorded as British : — 



Hieracium Schmidtii Tausch.— Though this name is used syn- 

 onymously with H. pallidum Biv., the plant to which Dr. Linde- 

 berg applied it differs so conspicuously from any plants I have 

 hitherto seen, either growing or in our herbaria, that I cannot 

 doubt its being a new form to Great Britain. It occurred abun- 



