USTILAGINACEAE 401 



on germination producing a short, septate promycelium, 

 which bears minute, lateral, and terminal secondary 

 spores. 



Ustilago avenae, Jensen. — Spore-mass blackish-brown, 

 soon pulverulent, formed in the ovary ; spores globose or 

 broadly elliptical, 6-8 ^ diam., or 7-9x6-7 /x, delicately 

 verruculose ; promycelium septate, sporidiola oblong, 

 produced at the septa. 



Var. levis, Kell. and Swing., 11. Ref. Agr. Kansas, p. 25, 

 tab. 5, f. 56-60. — Spores smooth and slightly darker in 

 colour than in the type form. 



Ustilago tritici, Jensen, in Kell. and Swing., 11. Rep. 

 Agr. Kansas, p. 214 and 262, tab. 2 and 6. — Spore mass 

 dark olive-brown, loose, formed in the ovary ; spores 

 ovoid, elliptic, or subglobose, 5'S-7'SXS-6 /u, dilute olive, 

 minutely verruculose ; promycelium branched, septate ; 

 secondary spores. 



Forma folicola, P. Henn., Zeitschr. fiir Pflanzenkr., 1894, 

 p. 139. — Developed on leaves and leaf-sheaths of Triticum 

 vulgare; spores either quite smooth, or dehcately punc- 

 tulate, yellowish olive-brown, 4-5-7 X4'5-6 [i.. 



Ustilago nuda, Kell. and Swing., 11. Rep. Agr. Kaftsas, pp. 

 215 and 277, pi. 2, f. 7-17. — Spore-mass olive-brown, pro- 

 duced in the ovary, soon free and powdery ; spores ellip- 

 tical to globose 5-7 X 5-6 ft olive-brown. The promycelium 

 does not produce secondary spores, but forms a sparingly 

 branched, septate mycelium. 



Ustilago hordei, Kell. and Swing., 11. Rep. Agr. 

 Kansas, pp. 215 and 268, pi. 2, f. 2-6. — Spore-mass black, 

 compact, not becoming pulverulent, and enclosed in the 



2 C 



