USTILAGINALES %2, 



2. Promycelium 1-5-celled, bearing lateral and terminal spores ; (parasitic 



on various hosts). UsTiLAGO. * 



Promycelium 2-celled, each bearing a number of spores on sterigmata ; 

 (parasitic on Cyperaceae). Anthracoidea. 



3. Spore-masses composed of a few cells ; (a single Californian species 



on Atriplex. ) PoiKlLOSPORiUM. 



Spore-masses composed of numerous clustered cells. 4. 



4. Chlamydospores loosely united, often falling apart at maturity. 



SOROSPORIUM, f 



Chlamydospores closely united together. 5* 



5. Promycelium with both lateral and terminal spores. TOLYPOSPORIUM. 

 Promycelium branched, with single lateral spores. Tolyposporella. 

 Promycelium with a single terminal spore. Thecaphora. 



Of the above genera, Ustilago is by far the largest, containing 

 nearly two hundred species of which at least one-third are Amer- 

 ican, (/y. 6. f. I, 2.) U. 2"^^^? forms the smut of corn, U. avctiae 

 the common smut of oats, U. tritici the common smut of wheat ; 

 U. /o7tgissi?na iorms, long brown lines on the leaves of Glyceria; U. 

 violacca appears in the anthers of Diajithits and other members 

 of the pink family, U. oxalidis in the ovaries of Oxalis, and 

 many other grasses and dicotyledonous plants are similarly af- 

 fected. Our American species need a careful comparative study, 

 a statement equally true for the entire order. 



Schizonella is represented by a single species parasitic on the 

 leaves of Carex Pemisylvanica forming narrow interrupted black 

 lines in early spring. Sorospormjfihs.s several species on grasses, 

 besides S. saponariae found in the ovaries of Sapoiiaria and other 

 pinks. Tolyposporella has a single species formed underneath 

 the leaf sheath of CJirysopogon 7iiitatis, Tolyposporiitni has sev- 

 eral species on Jimciis and various grasses, while Thecaphora has 

 a few species on Convolvulus and various members of the pea 

 family. 



Family 2. Tilletiaceae. 



This family contains genera still more diverse from each other. 

 While some like Tilletia and Urocystis are similar in general ap- 



* The genus Cirttradia is sometimes separated from Ustilago. 

 f In this condition there is often difficulty in distinguishing this genus 

 from Ustilago. 



