USTILAGINALES 83 



2. Promycelium i-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 



an A triplex.) POIKILOSPORIUM. 



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. (PL 6. f. /, 2.) U. zeae forms the smut of corn, U. avenae 

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

 U. longissiina forms long brown lines on the leaves of Glyceria; U. 

 violacea appears in the anthers of Dianthus 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 Pennsylvania} forming narrow interrupted black 

 lines in early spring. SorosfloriumhsLS several species on grasses, 

 besides 6". saponariae found in the ovaries of Saponaria and other 

 pinks. Tolyposporella has a single species formed underneath 

 the leaf sheath of Chrysopogon nufans, Tolyposporimn has sev- 

 eral species on Juncits and various grasses, while TJiecapJiora 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 Cintractia is sometimes separated from Ustilago. 

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

 from Ustilago. 



