256 GRASSES OF IOWA. 



grass {Arrenatherum avenaceani), Broiuusinermis, sheep's fescue 

 [Festuca ovina), tall meadow fescue {Festuca elatior), etc 



The fungus is closely related to stinking smut of wheat. 

 The spores germinate in the same way and probably enter its 

 host when the seed germinates. There is this important dif- 

 ference between the two species, this smut does not aifect the 

 "seed" in the same way. Its life-history is also somewhat 

 different. The stinking smut is at most very short-lived, while 

 this species is certainly a perennial. The destructive work of 

 stinking smut comes on at a time when flowers and seed are 

 forming. TUlefia striaeformis appears long before, perhaps 

 soon after the first leaves come out early in spring. In Iowa I 

 have Doticed it about the middle of May; itcontinues, however, 

 to develope on the younger leaves till the middle of June, when 

 often the bracts of the flowers become affected. Last spring 

 in on? of the meadows on the college farm a large number of 

 young plants were affected; the loss was very considerable. 

 The plants were shorter and marked with longitudinal lead 

 c )lored stripes, often extending to the very tips of the leaf. 

 When these lead colored patches are torn open a black pow- 

 dery ma?s, the spores, are exposed. 



As the plants become older the epidermis of these lead 

 colored patches breaks ani thus exposes the spores. The 

 constant action of the wind soon causes the leaf to be torn up 

 into shreds. The affected plaGts never become so tall as the 

 adjoining ones, seldom fruiting well. I think there can be Vc ry 

 little doubt that the fungus is a perennial as the following will 

 illustrate. During the spring of If^S? and 1888 I observed a 

 small bunch of timothy in the Missouri Botanical GardenatSt. 

 Louis, every leaf and stalk in the bunch was affected. Both 

 seasons it was found on the same plants. Here at Ames, also, 

 I have ssen the smut on the same plants for two seasons. 



THE GENUS UROCYSTIS. 



This genus contains several parasites destructive to our 

 cultivated plants. Our grasses are effected by two of these, 

 the rye smut and the wild rye smut. 



RYE SMUT. 



This fungus ( Urocystic occulta, Wallr.), first described by Wall- 

 roth* in 1883, has been repeatedly observed in various European 



*F1. Crypt. Germ. 2: 212. Erysibe occulta, Trocystlc occulta (Wallr.) Rabenh. 

 Klotzsch Herb. Myc. No. 39.1. Fung. Eur. I7SU. 



