472 
IOWA ACADEMY OF SCIENCE Vol. XXIV, 1917 
The causal organism for rust on alsike clover has been given 
as Uromyces trifolii (Hedw. f.) Liro and Nigredo trifolii (Hedw. 
f.) Arthur, thus placing it with the rust on red clover in the 
former case and with that on white clover in the latter. 
The question which naturally arose as to its disposition can 
now be answered in a more satisfactory manner. As the aecial 
stage has been definitely located and connected in the life cycle 
by inoculations, it shows the rust to be long cycled, autoecious, 
with all spore forms. Inoculations show that none of the spore 
forms have been transferred to the other clovers. The measure- 
ments show many morphological differences, at least as many 
as exist between the rust on white and on red clover. Nigredo 
fallens (De.s.) Arthur, is the rust on red clover; Nigredo trifolii 
(Hedw. f.) Arthur, the rust on white clover. 
If the rust is to be named, probably Nigredo hybridi Davis 
would be in best keeping with Arthur’s classification, which 
transfers the rust from the genus Uromyces to that of Nigredo. 
Otherwise Uromyces hybridi Davis. 
Department of Agriculture, 
State Teachers College. 
LilTERATURE ClTED. 
1. Davis , J. J., A Provisional List of the Parasitic Fungi of Wis- 
consin, Part II, 17, 984, 1914. 
2. Arthur , North American Flora (Urediniales) , 3, 219, 1912. 
3. Saccardo, Sylloge Fungorum, 21, 542, 1912. 
4. Saccardo , Sylloge Fungorum, 7, 534, 1888. 
5. Kern, F. D., Rusts of White and Red Clover: Phytopath, 1, 
3-6, 1911. 
6. Sydow, Monographia Uredinearum, 2, 131-133, 1910. 
7. Duggar, Fungous Diseases of Plants, p. 395, 1909. 
8. Ivanoff, Untersuchunger liber den Einfluss des Standortes auf 
den Entwickelingsgang und den Peridenbau den Uredineen: Centralblat 
fiir Bakter und Parasitet, 18, 265-470-655-661, Fig. 33, 1909. 
9. Liro, Acta Societatis pro Fauna et Flora Fennica, 29, 11, 1906. 
10. Howell, J. K., Bui. Cornell Univ. Ag. Exp. Sta.,. 24, 129-139, 1890. 
U. Trifolii-Bot. Gaz., 15:228, 1890. 
11. Pammei, L. H., Bui. Ia. Ag. Exp. Sta., 13, 51-55, May, 1891. 
12. Pammei, L. H., Bui. Ia. Ag. Exp. Sta., 61, 141, July, 1902. 
