I714 WEEDS AND PARASITIC FI.OWKRIXG PEANTS 



WEEDS AND PARASITIC FIvOWERING PLANTS. 

 1236 -Researches on the Dodder of Flax {Cuscuta Epi//num) in Germany.— 



Obersteim, in Illustriciie lamiivirtschaltlichc Zcitun-:, Year 36, Xo. jiS, pp. 525-526. 

 Berlin, Sept. 27, 1916. 

 Hitherto dodder has only appeared to a slight extent upon flax in 

 Germany. In the literature of the subject there are records of its appear- 

 ance in large quantities in Saxe-Altenbourg (1904), in Bavaria (1905-06) 

 in the Grand-Duchy of Reuss, in West Prussia and in Posnania (1908). 

 During the last year it has also been reported from Silesia having proba- 

 bly been imported with flax from Russia (i). 



The writer profited bj^ this opportunity to investigate the germination 

 of the seeds and the question of their different plant hosts. The work was 

 carried out in the vSeed Testing Station of the Silesian Chamber of Agri- 

 culture. On 13 April 1916, 100 seeds of dodder were sown and allowed to 

 germinate in 4 sets of sterile sand. After 3 days 29, 30, 19 8,nd 39 per cent 

 of the seeds had begun t5 germinate; 3 days later the percentages were 

 increased b}- 15, 15, 19 and 5 respectively; 10 days after sowing the per- 

 centages of seeds which had germinated were 45, 48, 51 and 44. A germi- 

 nation experiment carried out at the same time with C. TrijoUi and C. 

 racemosa, but using the method emploj^ed for clover, gave the following 

 results: with C. Trifolii the maximum number of seeds which had ger- 

 minated after 24 hours was 2 per cent; while with C. racemosa the percent- 

 ages were 4, 8, 4 and 9 after 5 days and 18, 25 16 and 26 respectively 

 after 24 days. 



All these experiments therefore confirm the opinion which is gener- 

 ally held, namely, that the dodder of flax, owing to its rela.tively high 

 germination, is well adapted to the short duration of its principal plant 

 host. 



Pot experiments with dodder seeds gave flourishing plants from June 

 and Jul}^ onwards; they developed equally well on red clover a.nd on flax, 

 although the former appears to suit them less well. The red clover however 

 suffered less than did the flax which was often completely choked during 

 the course of its growth. Good flowers were only obtained when the flax 

 was slightly attacked by dodder. The dodder flowers equalh' well on red 

 clover and on flax if the pots are watered from time to time. 



Dodder which was grown on red clover produced ripe seeds just as 

 it does on flax. Ripe seeds were also obtained from dodder on Lathyrus 

 Aphaca and on Vicia hirsnta, which had accidentally found their way 

 into the pots with the flax. 



The results embodied in this paper are not in entire agreement with 

 those obtained by previous workers so that further work upon the sub- 

 ject is still required. 



(i) vSee B. January, 1913, N° 75. [Ed.). 



