PHRAGMIDIUM 



297 



7. Phragmidium Rubi Wint. 



Puccinia mucronata var. Rubi Pers. Disp. Meth. p. 38. 



Phragmidium Rubi Wint, Pilze, p. 230. Plowr. Ured. p. 224. Fischer, 



Ured. Schweiz, p. 418, f. 290. Sacc. Syll. vii. 745 p.p. Sydow, 



Monogr. iii. 141. 



Spermogones. Epiphyllous, in minute clusters. 



J-kidiospores. Coeomata hypophyllous, roundish, or on the 

 nerves elongated, often in little 

 groups,surrounded by clavate para- 

 physes ; spores resembling those 

 of P. violaceum. 



JJredospores. Sori hypophyl- 

 lous, scattered; spores smaller 

 than those of P. violaceum. 



Teleutospores. Sori small, on 

 brownish spots, round, scattered, 

 seldom more than ^mm. diam., 

 black; spores cylindrical, of 4 — 7 

 (mostly six) cells, rounded above 

 and mucronate with a colourless 

 acute papilla (5 — 10 fi long), not 

 constricted, rounded below, brown, 

 beset with numerous little warts, 

 70—115x28—32^, with three 

 (or two) germ-pores to each cell ; 

 pedicels hyaline, as long as or 

 longer than the spore, swollen at 

 the base. 



Fig. 225. Ph. Rubi. Teleuto- 

 spore x 360 ; uredospore x 600 ; 

 a, teleutospore, boiled in lactic 

 acid for one minute, x 600. On 

 R. fruticosus. 



On Rubus fruticosus, R. caesius, P. saxatilis (?). Rather less 

 common than P. violaceum. July — September. (Fig. 225.) 



Distinguished from P. violaceum by its smaller teleuto-so*-i, and by the 

 predominance of six-celled spores ; the spots on the leaves are usually 

 much less brilliant in colour. The form on Rubus saxatilis may be a 

 distinct species, P. Rtibi-saxatilis Liro, Ured. Fenn. 1908, p. 421 ; Sydow, 

 Monogr. iii. 144. 



Distribution : Europe. 



