CLINTON: NORTH AMERICAN USTILAGINEAE. 
383 
over the surface or in a continuous line closely following the mar¬ 
gin, purplish, rupturing usually only on one side of leaf; spores 
light to dark purple, ovoid or ovate to spherical, often somewhat 
angled, usually abundantly but minutely verruculose, chiefly 13-19 y 
in length. 
Host: Polygonum viviparum , Colo., Wyo.; Greenland. 
This European species has rarely been reported from North 
America. There are two forms — one growing in pustules over 
the leaf (pustulata ) and the other in lines ( margincilis ) closely fol¬ 
lowing the margin. There seems to be no real reason for consider¬ 
ing these distinct species as did Schroter, since they appear to 
have no difference in spore characters and since some leaves contain 
both forms. Trelease (Harriman Alas. Exp., Crypt. Bot., 5 : 35. 
1904) has recently described a new variety, infloresceyitiae, said to 
differ from the species in the smooth spores which occur in the 
inflorescence. Brefeld has described the germination : 23. 
Sphacelotheca DeBy. 
Verg. Morph. Biol. Pilze, 187. 1884. 
(Endothlaspis Sor., Rev. Myc., 12: 4. 1890.) 
Type: Sphacelotheca Hydropiperis (Schum.) DeBy. ( Uredo Hydropiperis 
Schum.) 
Host: Polygonum Hydropiper. Eur. 
Sori usually in the inflorescence, often limited to the ovaries, pro¬ 
vided with a definite (more or less temporary) false membrane cov¬ 
ering a dusty spore mass and a central columella (usually chiefly of 
plant tissues) ; false membrane composed largely or entirely of defi¬ 
nite sterile fungous cells which are hyaline or slightly tinted, oblong 
to spherical, and usually more or less firmly bound together; spores 
simple , usually reddish brown, developed in a somewhat centripetal 
manner as in Cintractia, small to medium in size; germination as in 
Ustilago. 
DeBary based this genus on the single species S. Hydropiperis / 
recently the writer has placed here a number of additional sji>ecies 
