402 PLANT DISEASES 



ovary ; spores globose or subangular from mutual pressure, 

 blackish-brown, 6-7*5 /* \ promycelium 3-4-septate, pro- 

 ducing secondary spores. 



Ustilago maydis, Corda. Forming large tubercular 

 masses on the inflorescence, often many centimetres in 

 diameter, also corrugated pustules on the leaves ; pustules 

 at first covered by the silvery epidermis, then olive-brown 

 and pulverulent ; spores globose or broadly elliptical, 

 8-13X8-11 ju, pale brown, pellucid, minutely aculeate; 

 promycelium 3-4-septate, bearing fusoid secondary spores 

 at the septa and apex. 



Ustilago sorghi, Passer. Spore-mass blackish-brown, 

 formed in the ovary or in the anthers, soon pulverulent ; 

 spores globose, oblong, or angular, 5-9-5 X4~5'5 p, epispore 

 smooth, pale olive; promycelium cylindrical, constricted 

 near the spore ; secondary spores oblong, numerous. 



Ustilago cruenta, Kiihn. Spore-mass olive-brown, 

 formed at the apex of the culm and in the branches of 

 the inflorescence, forming large reddish-brown patches, 

 rarely in the ovary, the attacked branches are usually much 

 bent and distorted ; spores globose or broadly elliptical, 

 5-12x5-9 /*; epispore olive-brown, smooth; promycelium 

 cylindrical, generally 3-septate ; secondary spores elliptic- 

 fusoid, produced laterally and at the apex. 



Ustilago reiliana, Kiihn. Pustules formed in the 

 inflorescence, often finger-shaped, at first enclosed in a 

 silvery membrane, then becoming pulverulent, blackish- 

 brown ; spores subglobose, pellucid brown, delicately 

 echinulate, 9-12 p diam. ; promycelium septate, producing 

 elliptical secondary spores. 



Ustilago emodensis, Berk., Hook, Journ. Bot., vol. iii. 



