ON POLYGONACE^E 115 



U. Rumicis Wint. Krypt. Fl. i. 145. Plowr. Ured. p. 135 p.p. Sacc. 

 Syll. vii. 544. Sydow, Monogr. ii. 238. Fischer, Ured. Schweiz, 

 p. 9, f. 8. 



Uredospores. Sori amphigenous, on coloured spots, round, 

 minute, scattered, soon naked, 

 pulverulent, cinnamon ; spores 

 subglobose to ellipsoid, sparsely 

 echinulate, pale-brown, 20 — 28 x 

 18 — 24 fi, with two (more often 

 three) germ-pores. Fig . 67 _ Um Rumicis , Teleuto- 



Teleutospores. Sori similar. s P ores and uredospore, on R. 



obtuslfolius. 



but darker ; spores subglobose to 



pvriform, with a hemispherical hyaline papilla, often narrowed 

 below, smooth or nearly so, brown, 24 — 35 x 18 — 24 yu. ; epispore 

 rather thick ; pedicels thin, hyaline, deciduous. 



On Rumex conglomeratus, R. crispus, R. Hydrolapathum, 

 R,. nemorosus, R. obtuslfolius, and perhaps others. May — 

 September. Common. (Fig. 67.) 



The spots on the leaves are small, round, and of various colours ; often 

 the chlorenchyma in the immediate neighbourhood retains its green colour 

 long after the rest of the leaf has become faded and yellow. 



It will be noticed that the spores of U. Rtimicis are exactly like those 

 of U. Ficariae, and for this .reason Tranzschel was led to suspect some 

 connection between the two, such as he demonstrated to exist between 

 P. fusca and P. Pruni-spinosae, whose teleutospores are equally alike. In 

 1905 he reported that he had produced an secidium on Ranunculus Fiearia 

 from the spores of U. Rumicis ; still later, he repeated this statement 

 (1909), and added that he had infected Rumex obtusifolhis with secidio- 

 spores from R. Fiearia. Other experimenters (Bubak, Krieg) have been 

 unable to repeat the former of these infections ; they could only produce 

 the secidium on R. Fiearia with the spores of Uromyces Poae. It has 

 been suggested that there are two eecidia on R. Fiearia, one belonging to 

 U. Poae and the other to U. Rumicis ; I have tried to infect R. obtusifolius 

 with secidiospores from R. Fiearia, brought from a place where the secidium 

 on it and the Uromyces on It. obtusifolius were both very abundant, but 

 the attempt failed. Krieg (Centralbl. f. Bakt. 1906) obtained uredo- 

 spores on R. Acetosa with iccidiospores from R. Fiearia, but the same 

 material infected species of Poa (especially P. trivialis), and the possibility 



8—2 



