116 UROMYCES 
of contamination by foreign spores was not entirely excluded in his 
experiments. Judgment on this point must be suspended. 
DistRIBUTION: Europe, Algeria, Asia Minor, Africa, Cali- 
fornia, Chili. 
28. Uromyces Acetose Schrot. 
Uredo bifrons DC. ; Cooke, Handb. p. 528 ; Micr. Fung. p. 217, pl. vii. 
figs. 137—9. 
Uromyces Rumicis Wint.; Plowr. Ured. p. 135 p.p. Fischer, Ured. 
Schweiz, p. 9 (not f. 8) p.p. 
U. Acetosae Schrét. in Rab. Fung. Europ. no. 2080 (1876). Sace. Syll. 
vii. 587. Sydow, Monogr. ii. 241. 
[Spernogones. Honey-coloured, clustered. 
Aicidiospores. AKcidia amphigenous or on the petioles, in 
dense clusters (up to 1 cm. broad), cup- 
ff shaped, whitish-yellow, with a cut and 
revolute margin; spores nearly smooth 
or very minutely punctate, clear-yellowish, 
Fig. 68. U. Acetosae. 18—21 x 12—18 p.] 
Teleutospores, on Uredospores. Sori amphigenous, often 
ceca 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 w; epispore about 24, 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—26 x 20—24 py; Bpinne 
rather thick ; pedicels thin, hyaline, deciduous. 
On leaves and petioles of Rumex Acetosa, R. Acetosella. 
May—September. Not uncommon. (Fig. 68.) 
Allied to U. Rumieis, but U. Acetosae has shorter spores (of both kinds) 
and the hyaline papilla of the teleutospores is almost always wanting. 
The «cidium 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. 
