278 GRASSES OF IOWA. 



Teleuto sori usually on the under surface of the leaves; some- 

 times on both surfaces, singly or in groups, confluent, the 

 edges of the epidermis of the edges of the sori straight. 

 Teleuto spores two-celled, obovate to elliptical, constricted at 

 the middle. Apex rounded and somewhat obtuse. Spores 

 30-45 X 15-22". Pedicels as long or longer than the spores. 

 This species is most troublesome in this state on Anclropogon 

 scoparius. In some cases over large areas a large number of 

 leaveSihave been infested with the fungus. It is especially 

 manifest during the month of September and October, uredo 

 spores being most abundant during the month of August. 



Switch grass rust {Puccinia eamulata Schweinitz). — This 

 species was described by Schweinitz* and occurs upon several 

 different genera, notably Tricuspis seslirioicles, Panicum virga- 

 turn, P. capillare and Eragrostis pectinacea. 



Sori numerous, usually on the upper and lower surfaces of 

 the leaf. They are most abundant on the lower. The uredo 

 sori, brownish, elongated, frequently confluent, irregular. 

 Spores sub-globose, 15-20" in diameter, echinulate. Teleuto 

 .sori irregular, elongated, frequently confluent, black. The 

 epidermis broken, forming a rim around the edge, lacerated. 

 Spores constricted in the middle. Apex obtuse or acute, 30- 

 48" by 15-21". Pedicels long or longer than the spores. 



Puccinia poarum, Nielsen,! affects Poa an7ivia. The pustules or 

 sori of the uredo stage are orange-colored, round to elliptical, 

 provided with sterile threads known as paraphyses. The uredo 

 spores usually have six germ pores. The spores are round or 

 somewhat elongated and spiny. The teleuto sori are black or 

 dark brown, oblong to linear, without sterile threads, long 

 remain covered by the epidermis, the spores are usually two- 

 celled, brownish-yellow to dark brown, provided with short per- 

 sistent pedicels. 



Puccinia anthoxanthi occurs upon the Anthoxanthum odoratum. 

 The spores of this species are extremely variable. Ordinarily 

 they are much longer than broad, and with a rather stout, per- 

 sistent pedicel. The uredo spores are minutely roughened. 

 The Puccinia phragmitis is quite common on Phragmites communis. 

 The secidium of this fungus occurs upon a species of Rumex. 

 A second Puccinia has been recognized upon Phragmitis, e. g., 

 Puccinia magnusiana Koern. The tecidium of this occurs upon 



♦Saccardo. Syll. Fung. 7: 663. Burrlll. Parasitic Fungi of Illinois. 201. 

 tSaccardo Syll. Fung. 7: 62.5. Nielsen. Bot. Tlds. Ill, 2; 26. 



