ON COMPOSIT/E 



153 



purplish spots, scattered, minute, punctiform, soon naked, 

 brown; spores few, globose to ovate, echinulate, brown, 22— 

 32 x 19 — 26yti, with two germ-pores. 



Teleutospores. Sori similar, but darker ; spores ellipsoid to 

 oblong, rounded at both ends, not thickened above, not con- 



Fig. 105. P. variabilis. /Ecidia, on leaf of Taraxacum, and teleutospore. 



stricted, delicately verruculose, brown, 28 — 40x18 — 25 /*; 

 epispore thin ; pedicels hyaline, about as long as the spore, but 

 deciduous. 



On Taraxacum officinale and its variety palustre. July — 

 October. Not common. (Fig. 105.) 



Plowright and Soppitt both proved, Dy laying leaves affected with the 

 aecidium of this species on healthy plants of Taraxacum, that the uredo- 

 and teleutospores were produced in about fourteen days. In July the 

 three spore-forms may be found on the same leaf. 



There are two forms of eecidium found upon Taraxacum ; one, jffcidium 

 Grevillei Grove ( = jE. Taraxaci Grev. non K. et S.), spreads pretty 

 uniformly over the whole leaf in "numerous little clusters with single ones 

 scattered between them," as Greville describes it (Flor. Edin. p. 444) — the 

 other, SE. Taraxaci K. et S., forms large round clusters, and belongs to 

 P. silvatica. Fischer points out that the two recidia differ in the form of 

 their peridium cells, those of P. variabilis having the membrane thickened 

 on the inner side, while those of P. silvatica have the outer wall most 

 strongly thickened. He states, furthermore, that it will be found that 

 this difference is characteristic in general of autcecious and hetercecious 

 species respectively. It is not, however, universally so, e.g. the secidium 

 of P. albescens has the outer wall much more strongly thickened, although 

 it is autcecious. 



Greville figures the teleutospores of his species (Scot. Crypt. Flor. pi. 75) 

 as having either one or both of the cells sometimes divided by a vertical 

 septum. 



Distribution : Switzerland, Sweden. 



