OIDIUM. 287 



Oidium leucoconium, Desmaz., Ann. Sci. Nat., 1829, xiii. 

 p. 102, t. 6, f. 1-2 ; Sacc., Syll., iv. n. 190. 



On stems, leaves, and calyces of cultivated and wild roses. 

 The conidial condition of Sphaerotheca pannosa. 

 Oidium Tuckeri. Berk. 



Tufts small, densely gregarious, often confluent and 

 forming broad white patches of a loose, open texture, whitish, 

 becoming dingy ; sterile hyphae with lobed haustoria, ending 

 in short, suberect, colourless couidiophores ; conidia elliptical 

 or oblong, ends obtuse, in short chains of 2-3, 25-30 x 15-17, 

 granular within, hyaline. 



Oidium TucJceri, Berk., in Gard. Chron., 1847, p. 779 ; Sacc., 

 Syll., iv. n. 191. 



On living leaves and fruit of vine. 



Oidium farinosum. Cooke. 



White, mealy, eifused, covering the young leaves and 

 twigs as if dusted with flour; threads simple, breaking up 

 into elliptical, truncate joints or conidia, which are smooth, 

 28-30 x 12 p.. 



Oidium farinosum, Cooke, Grev., xvi. p. 10. 



On living leaves and twigs of apple. 



Oidium erumpens. Cke. & Mass. 



Tufts greyish-white, erumpent, rather compact, becoming 

 dark-coloured with age, formed on the under surface of the 

 leaves; conidia subglobose, at first rather quadrate, due to 

 mutual pressure, concatenate, hyaline, 5 x 7 p.. On short 

 stout conidiophores. 



Oidium erumpens, Cke. & Mass., Grev., xvi. p. 49. 



On living leaves of Eivea hypocrateriformis. 



Oidium chrysanthemi. Kab. 



Effused, white ; sterile hyphae creeping, aseptate, hyaline ; 

 conidia in long chains, elliptic-oblong, rounded at both ends, 

 granular inside, hyaline, 40-50 X 20-25 p.. 



Oidium Chrysanthemi, Eabenh., Hedw., i. p. 19, t. 3, f. 1 ; 

 Sacc., Syll., no. 199. 



On leaves of cultivated species of Chrysanthemum. 



Oidium aceris. Rabach. 



Densely caespitose, whitish with a red tinge ; conidia 

 ovoid or broadly ovate, often truncate, 25-45 X 8-12 p.. 



