Further Studies on the Apogamy and ubrarv 

 Hybridization of the Hieracia ^!otamcal 



(Experimental and Cytological Studies on the Hieracia, by C. H. Ostenfeld QARt>CN- 



and O. Rosenberg, Part III) 

 by C. H. Ostenfeld, Köbenhavn 

 (with Plate 4). 



Contents. 



pag. 



Introduction 241 



I. Apogamy (Castration Experiments) 242 



1. Subg-nus Stenotheca 243 



2. Subgenus Archieracium 244 



3. Subgenus Pilosella 253 



II. Hybridization Experiments . 256 



I. H. pilosellax aurantiacum 257 



3. H. auricula X aurantiacum 257 



3. H. excellew, X. aurantiacum 261 



4. H. exccllcn-i X piloaclla 205 



General results of the crossing 266 



III. Apogamy and its Relation to Polymorphism 267 



IV. The Importance of Hybridization tor the Origin of New Species, with special 

 regard to Hieracium 276 



Literature 282 



Introduction. 



In 1906 I published a paper on some experimental investigations 

 on the apogamy and hybridization of the Hieracia (Ostenfeld 1906, 

 1907). It was the beginning of rather extensive studies on the re- 

 production of this interesting genus, which studies I am still pursuing 

 and of which I shall here publish some results. I do not mean to 

 say, however, that the investigations are near their end, far from it, 

 and I can very well repeat what I wrote in 1906 (1. c, p. 247), 

 "that at present we are only at the very beginning of our knowledge 

 of these phenomena". In the meantime, however, I have discovered 



Induktive A)jst:i[iiniiings- und Vererbungslehre. III. 1(3 



