Further Studies on the Apogamy and Hybridization of the Hieracia. 243 



the genus Hicracimn we have apogamic and non-apogamic species 

 together with transitions between both kinds. The three subgenera 

 are in this respect not quite alike; the subgenus Stenotheca representing 

 the most primitive stage with typical fertilization: the subgenus 

 Pilose/la being intermediate as it comprehends both apogamic and 

 typically fertilizing species, nevertheless mostly apogamic; and the 

 subgenus Arcltieraciitvi representing the most developed stage with 

 nearly all species apogamic. only excepting the H. umbcllatnm group.'" — 

 This main result is still valid, but several details have been found, 

 enlarging our knowledge of the phenomena. 



/. Siibgenns Stenotheca. 



For the subgenus Stenotlicca I have nothing really new to add; 

 my plantings of the species of this subgenus have not been successful. 

 These North American species seem to require a longer and warmer 

 summer than we have in Denmark. 



In the spring of 1908 I succeeded in getting seeds of H. Gronovii L., 

 H. longipihun Torr, and H. scabntm Michx.; they were sown immediately' 

 at the end of April, but did not reach flowering that year. After 

 wintering in pots in a frost-less place they were planted out in 1909, 

 but is was not till towards the end of September that a few speci- 

 mens of H. Gronovii came to flowering, and then it was too late to 

 try castration. No fruit, further, was developed in any of the plants 

 left to themselves. 



My plants of the only European species of this group, H. stati- 

 cifolium Vill., did not fruit in 1909, neither without nor after castra- 

 tion, so that I have nothing positive to say about this species either. 



The plants of H. venosuni L. and H. Gronovii L. used for my 

 experiments in 1905 (Ostenfeld 1906) and their offspring died already 

 in the winter 1906 — 1907; they did not seem to be able to endure 

 our winter, and in the summer of 1906 they did not flower early 

 enough to give ripe fruits. Thus I cannot say anything more about 

 the reproduction in the subgenus Stenotheca than in my paper of 1906, 

 viz., that both the two hitherto examined species require 

 normal fertilization in order to produce seeds capable of 

 germinating. 



It will be of great importance to have some more species of this 

 subgenus examined, and I think it a promising task to an American 

 botanist to subject this matter to examination. He will also be able, 



