1 hi DTROMYCES 



of contamination by foreign spores was not entirely excluded in his 

 experiments. Judgmenl on this point must be suspended 



DISTRIBUTION: Europe, Algeria, Asia Minor, Africa, Cali- 

 fornia, Chili. 



28. Uromyces Acetosae Schrot. 



Uredo bifrons I >l '. ; Cooke, Eandb. p. 528 ; Micr. Fung. p. 217, pi. vii. 



Bgs. 137—9. 

 Uromyces Rwmicis Wint. ; Plowr. Ured. p. 135 p.p. Fischer, Ured. 



Schweiz, p. 9 (not f. 8) p.p. 

 ('. Acetosae Schrot. in Rab. Fung. Europ. no. 2080 (1876). Sacc. Syll. 



vii. ">37. Sydow, Monogr. ii. 241. 



[Spermogones. Honey-coloured, clustered. 



J-'.riil iospores. iEcidia amphigenous or on the petioles, in 

 dense clusters (up to 1 cm. broad), cup- 

 shaped, whitish-yellow, with a cut and 

 re volute margin ; spores nearly smooth 

 or very minutely punctate, clear-yellowish, 

 18—21 x 12— 18/i.l 



Fig. 68. U. Acetosae. r J 



Teleutospores, on Uredospores. Sori amphigenous, often 



seated on red or purple spots, scattered or 

 circinate, minute, pulverulent, cinnamon ; spores subglobose to 

 ellipsoid, finely and densely verruculose, yellowish or pale 

 brownish-yellow, 18 — 25 x 17- — 22 /x ; epispore about 2|/i, thick, 

 with three germ-pores. 



Teleutospores. Sori similar, but dark-brown ; spores sub- 

 globose to ellipsoid, not thickened above, or rarely with a paler 

 and very minute papilla, rounded below, beset with very minute 

 warts arranged in lines, brown, 21 — 26x20 — 24 /j,; epispore 

 rather thick ; pedicels thin, hyaline, deciduous. 



On leaves and petioles of Rumex Acetosa, R. Acetosella. 

 May — September. Not uncommon. (Fig. 68.) 



Allied to U. Rwmicis, but U. Acetosae has shorter spores (of both kinds) 

 and the hyaline papilla of the teleutospores is almost always wanting. 

 The secidium has not been found in Britain, but the other stages are 

 rather common : the uredo- and teleutospores are unusually alike, but can 

 be distinguished by the germ-pores and the fewer warts of the latter. 



