CLINTON: NORTH AMERICAN USTILAGINEAE. 
485 
hyaline to yellowish , firmly united, of small to medium size; germi¬ 
nation as in Doassansia. 
Tracya shows, perhaps, the highest development attained by the 
Tilletiaceae. Like Doassansia it is an aquatic form and this possibly 
explains, in part, the great differentiation of spore structure attained 
by these genera. There has been but a single species described. 
Very unfortunately the name proposed for the genus by Setchell 
had been used a few months earlier by Pierre for a genus of flower¬ 
ing plants. Sydow, who discovered this, renamed the genus after 
S. M. Tracy, of Mississippi. 
Tracya Lemnae (Setch.) Syd. 
Cornuella Lemnae Setch., Proc. Amer. Acad. Arts Sci., 26 : 19. 1891. 
Tracya Lemnae Syd., Hedw., Beibl., 40: (3). 1901. 
Exsiccati: Tracya Lemnae (Setch.) Syd., on Spirodela polyrrhiza , Seym. 
& Earle, Econ. Fungi Clinton Ust. Supp., C 55. 
Sori in the languishing fronds, rather indefinite, showing the 
spore balls as very minute clustered, or scattered opaque bodies; 
spore balls situated in the spongy parenchyma above lower epider¬ 
mis, consisting of a single layer of fertile cells within which is a 
loosely arranged network of brownish filaments, ellipsoidal to 
spherical, rather small, 50-100 y in length; spores yellowish, 
originating from ends of the filaments, firmly compacted, cubical, 
polyhedral or often more elongated radially, chiefly 10-12 y in 
length. 
Host: Spirodela polyrrhiza , Conn., Mass, (type), R. I., Wise. 
This fungus has been reported only on the above species of duck¬ 
weed, though the infected plants are often associated with Lemna 
minor. It is found in the old fronds after they have lost most of 
their chlorophyll, but it probably begins its existence strictly as a 
parasite. The germination has been reported by Setchell. Litera¬ 
ture : 160, 161. 
