CLINTON: NORTH AMERICAN USTILAGINEAE. 
431 
ing usually dusty sori with dark colored spores; and Entyloma, Bur- 
rillia, Doassansia, and Tracya the other, characterized by the pres¬ 
ence, usually, of sori embedded permanently in the tissues, and 
light colored spores. The eight genera include seventy-three species 
and three varieties from North America. 
Tilletia Tul. 
Ann. Sci. Nat., Bot., in, 7 : 112-113. 1847. 
Type: Tilletia Caries Tul. 1 
Host: Triticum vulgare, etc. Eur. 
Sori in various parts of the hosts, usually in the ovaries, forming 
a dusty spore mass ; spores simple , usually formed singly in the ends 
of the mycelial threads that disappear more or less completely 
through gelatinization , of medium to large size ; germination usually 
by a short promycelium which bears a terminal cluster of elongated 
sporidia that with or without fusing in pairs may, in nutrient solu¬ 
tions, give rise to a considerable mycelium bearing secondary air- 
sporidia. 
The germination distinguishes this genus from Ustilago ; it bears 
the same relationship to the Tilletiaceae that Ustilago does to the 
Ustilaginaceae. Many of the species, however, have never been 
germinated but have been placed here because of their large usually 
regular spores, which characters serve in general to distinguish 
them from Ustilago. Attention should be called to the hyaline 
sterile cells present in some species, evidently in some cases corre¬ 
sponding to undeveloped spores ; and to the hyaline membrane usu¬ 
ally more or less evident, apparently the remains of the investing 
fertile liypha. In many of the species the spore masses have an 
evident foetid odor. They are almost entirely confined to the 
Gramineae, some of the species causing serious loss to the cultivated 
cereals. Saccardo records 53 species; 19 species are found in North 
America. 
1 Tulasne’s T. Caries included other species of Tilletia besides the Tilletia 
Tritici of to-day, though this may properly be considered the type. 
