An Aecium on Red Clover, Trifoliurn pratense L. 



Geo. N. Hoffer. 



The aecia of Nigredo fallens (Desmaz.) Arthur are reported in the North 

 American Flora, Vol. 7, Part 3, 1912, as being uncertain. The rust Nigredo 

 trifolii {Hedw.f.) Arthur is unknown on red clover. 



Kern, U)ll, calls attention to the fact that the common rust on red 

 clover had long been ascribed to Uromyces trifolii (Hedw.) Lev. He men- 

 tions however, tliat Liro in 1906 pointed out that the rust of white clover, 

 T. repens, differs from that of the red clover both in structure and habit. 

 Kern distinguisheb Uromyces fallens (Desm.) Kern growing on Trifolium in- 

 carnatum L., T. medium L., and T. pratense L. from Uromyces trifolii (Hedw.) 

 Leu. which grows on T. incarnatum L., T. hybridum L. ard T. repens L., but 

 not on T. pratense L., by the fact that the urediniospores of Uromyces 

 fallens have scattered the germ pores. 



In the same paper Kern suggests, however, that he believes that the red 

 clover rust is heteroecious. There seems to be but a single uncertain report 

 of an aecial stage on red clover. The further fact that a number of similar 

 rusts of legumes ai-e known to be heteroecious led him to suggest that the 

 alternate host Dossibly belonged to some euphorbiaceous host of the group 

 to which Euphorbia commutala belongs. 



The writer has found aceia on the stems and leaves of the red clover. 

 It was impossible to grow aeciaspores on any red clover plants and be certain 

 that they gave rise to uredinia because of the lack of proper controls. The 

 evidence is circumstantial that they are the aecia of Uromyces fallens. 



The aecia were fo'nd on May 23, 1915. They developed on leaves of a 

 plant which had all the appearances of Trifolium pratense L., but the plant 

 was not in flower. Because of the difficulty in determining the host species, 

 the plant was dug up and transferred to the writer's garden. The plant 

 thrived. 



During the following two weeks a number of other leaves bore aeeia. 

 Several of these leaves were left on the plant to note the effect of the fungus 

 upon them. 



Later in July, the plant blossomed and its identity determined. Three 

 heads formed and developed during the summer. These were taken and form 

 part of the collection. 



Dr. J. C. Arthur, of the Purdue University Agricultural Experiment 

 Station, has given the writer his estimate of some previous collections of 

 aecia supposedly on red clover. None of these collections sent to him had 

 blossoms with them and because of similarity in the leaves of the various 

 species of clover they were not absolutely authentic. 



One of the above referred-to collections made by Mr. J. Dearness, at 



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