228 IOWA ACADEMY OF SCIENCES. 



dark colored masses, usually surrounded by a reddish 

 brown membranous covering. 

 Usfilctf/o A rend' (Pers.) Jens. 



Uredo segetum. g. Uredo, Pers. Syn. Meth. Fung. 224. 

 1801. 



Uredo carbo, g. avenge, Wallroth. Fl. Crypt. Germ. 217. 

 1833. 



Ustilago carbo. a vulgaris C. avenacea. Tul. Mem. Sur. 

 Ust. 



Ust. comp. aux. CJred. 80. 1847. 



Ustilago segetum var. avenge, Jens. Om. Korn. Brand. 

 61. 1888. 



Ustilago a vena? Jens. L. Char, des Cer. 4. 1889. 



Exsiccati Ell. & Ev. F. Col. 539. 

 Sey. & Ear. Ec. F. 81. 



Spore masses filling and destroying the ovaries, brownish 

 black; spores, subglobose, oval or elliptical smoky brown; 

 5-6 X 6-10 u; epispore minutely echinulate. 

 Host. — Avena sativa. 

 Specimen's from Iowa. — Herb. Iowa State College. 



(1), (5,) (6), (7), Ames, L. H. Pammel. 



(2), (3), (4), F. C. Stewart; Crypt. Dist. Iowa State 

 College A. M. A. 



(11) Ames, C. W. Carver; Ex. Herb. J. C. Arthur (1696) 

 Emmet Co. 



R. I. Cratty, Ex. Herb. Hume (1) Ames, A. F. Sample. 



Ustilago aveme was for many years included with 

 tritici and hordei under the name segetum until it was 

 determined by Jensen that it would not develop either on 

 barle} or wheat. Upon the strength of this knowledge he 

 separated it as U. avence. Kellerman and Swingle straight- 

 ened out the synonymy and found the name should be 

 Ustilago avenai (Pers.) Jens. 



This species is quite prevalent throughout the state but 

 has doabtldss been confounded with U. levis. Great dam- 

 age is wrought annually to the oat crop and the seed grain 

 should be much more generally treated than it now is. At 

 threshing time in Iowa, the smut spores are often present 

 in such quantities as to give rise to a stifling dust. 



