413 



Castrating Experiments witli Hieracium 

 and otlier Ciclioriece 



by 



C. H. Ostenfeld and C. Raunkiaer. 



(Summary of the preceding article.) 



The authors have made some experiments of castration with Hieradum- 

 species (see the names above) with the result that all the used species 

 produced fullgrown fruits after the castration, and consequently, 

 they behave as the Taraxacum-s^ecxes of which C. Raunkiaer has 

 proved that they are apo garni c, probably parthenogenetic. On the other 

 hand other genera of Cichoriece (see the names above) do not bear 

 fruits after castration. The experiments are made in the same way 

 as Raunkiaer's experiments with Taraxacum, viz. : by cutting off with a 

 razor the upper half of the un-opened flower-heads, so as to remove the 

 anthers and the stigmas as well as most of the corollas. The earliest 

 castrated species (Hieracium hyparcticum Almq.) has already given rise 

 to new plants. 



Examination of the stigmas of different species, both of Hieracium 

 and other genera of Cichoriece, showed that no pollen-grains were 

 seen germinating; and the authors have not succeeded in obtaining 

 germination of pollen-grains, laid in destillated water together with stigmas ; 

 also R. Lidforss and H. Mollsch (1. c.) say that it has been impossible to 

 make the pollen-grains of ComposiUe germinate. On the other hand the 

 present authors have seen pollen-grains with long tubes on the stigmas of 

 Dahlia variabilis, and consequently the Cichoriece seem to differ from the 

 other groups of Compositce. 



Botanisk Tidsskrift. 25. Bind. 



