402 PLANT DISEASES 



ovary ; spores globose or subangular from mutual pressure, 

 blackish-brown, 6-7 "5 /x ; 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 [J., 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 x 4-5*5 />t, 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 fJ'', 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 /x diam. ; promycelium septate, producing 

 elliptical secondary spores. 



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



