324 NATURAL HISTORY BULLETIN. 



thickened at the rounded apex, prominently tuberculate, pores 

 obscure. III. Teleutosori pulvinate, blackish-brown; teleu- 

 tospores elliptical or oblong, 16-22 by 35-62/A, dark-brown, 

 slightly constricted at the septum, apex obtuse, thickened, 

 pedicel firm, slender, tinted, once to twice the length of the 

 spore. 



EXvSIC. 



Sydow, Uredineen, 262, 1167. 

 Ellis and Everhart, N. Am. Fungi, 1851, 3475. 

 Ellis and Everhart, Fungi Columb., 1288. 

 Carleton, Ured. Amer., 33. 



This species is one of the most common of American grass 

 rusts wherever Sfiartina grows. Until recently (see Bot. 

 Gaz. 29 :275, and 34:9) it was not given autonomous rank, 

 but was associated with the rusts on Phragmitcs and Arun- 

 dinaria. In its teleutosporic stage it is especially conspicuous 

 on account of the large, blackish, and exceedingly numerous 

 sori, which come upon the upper and exposed side (morpho- 

 logical under side) of the leaves as they stand on the plants 

 in the field. When the leaves roll up in drying, the sori are 

 still outside and attract attention. 



The uredostage is of short duration, and is very rarely col- 

 lected. We are especially indebted to L. R. Jones of Ver- 

 mont and H. H. Hume, formerly of Iowa, for the collections 

 in the present distribution, search having been made particu- 

 larly for this purpose. The uredospores are remarkable for 

 their greatly thickened apices. By removing the spores from 

 an unbroken sorus with a point of a knife the spores with 

 the pedicels attached may be secured, as in 54^". 



The aecidiostage upon the various species of Fraxinus is 

 often so abundant as to attract marked attention. The clus- 

 ters of secidia may be small or they may cause hypertrophy 

 of the tissues and thickly cover swellings a half inch or more 

 in diameter. This is especially likely to occur when the mid- 

 rib or petiole of the leaf is attacked. The secidial cups, when 

 well grown, are long and cylindrical, which induced Schwei- 

 nitz, undoubtedly, to transfer the form to the genus Roestelia, 



