— 232 — 



planted into a larger pot, where they flowered in September. Sep- 

 tember 3 rd — 5 th ; 11 heads were castrated, but did not give any- 

 developed fruit. The intact heads gave, but sparingly, ripe fruits 

 (553 barren to 215 full); the full fruits have germinated in the 

 spring of 1906. As the plants stand in a closed cold-house, no 

 cross-fertilisation has happened. 



(3) H. auricula L. (s. I.); specimens transplanted to the Bo- 

 tanical Garden from the northern part of Jutland (Skagens Odde, leg. 

 M. L. Mortensen). July 9 th 1905; 7 heads were castrated, but the 

 heads all faded; also later castrations did not succeed. The intact 

 heads gave ripe fruits, rather copiously, except in the late autumn, 

 when nearly all fruits were barren. 



(4) R. sp., labelled H. lactaris, according to Mr. Dahlstedt 

 belonging to the group of H. umbellatum ; growing in the Hieracium- 

 plot in the Garden. August 14 th — 15 th ; 7 heads (the only remaining 

 ones, the main flowering period being over and ripe seeds developed) 

 were castrated, but none gave full fruits. 



(5) H. umbellatum, L., f. filifolium, growing together with the 

 foregoing species. Also of this form some few (10) unopened, late- 

 developed heads were castrated in August and September, but 

 without any positive result. 



(6) H. umbellatum L. f. dunense (revis. H. Dahlstedt) ; wild- 

 growing specimens. The experiments were carried out in the dunes 

 of North-Jutland near Tværsted and on specimens growing in their 

 natural places. The plants were very common in the dunes and 

 gave ripe and full fruits in abundance. July 25 th — 26 th 4905; 9 

 heads, belonging to three individuals, were castrated; some of the 

 heads began to develop, others faded in course of a week. As I 

 had to leave the place about a fortnight after, the experiments 

 were broken off August 5 th ; the half-developed heads were preserved 

 in alcohol and later examined thoroughly. It then appeared, that 

 the ovule had grown to a certain point, but no embryo was 

 formed; we are therefore justified in saying that no fructification 

 occurs after castration. 



(7) H. virosum Pall. ; seeds obtained from the Missouri Botanical 

 Gardens were sown in the spring of 1905, planted out in July, 

 flowered very sparingly in September. September 3 rd ; two heads 

 were castrated, but the one did not succeed ; the other gave 36 full 

 fruits (12 empty), which have germinated in the spring of 1906. — 



If we arrange the species used in experiments in 1903—05 



