ON GRAMINE.E 



279 



30—45 x 16 — 22 /z ; pedicels short, brownish, persistent ; an 

 occasional mesospore is found. 



Fig. 211. P. Poarum. Teleutospores ; a, uredospore on P. nemoralis; h, para- 

 physes with same; c, mesospore; rf, teleuto-sori on P. pratensis; e, typical 

 teleuto-sori of Uromyces Poae, on the same. 



/Ecidia on Tussilago Farfara, about May, June, and August, 

 September, very common ; uredo- and teleutospores on Poa 

 annua, P. nemoralis, P. pratensis, P. trivialis, about July, 

 August and October — December, common but easily overlooked 

 unless searched for. (Fig. 211.) 



First stated by Nielsen, the connection of the two hosts was demon- 

 strated by Plowright and Klebahn. This hetercecious Puccinia differs 

 from all others in having two generations in one year. The earlier crop 

 of secidia begins to appear in May, and is followed by the uredo- and 

 teleutospores on the surrounding leaves of Poa ; these germinate quickly 

 and the second crop of secidia is produced about August, and the second 

 generation of teleutospores may be found on Poa from October. The 

 latter germinate in the following spring, but according to Lagerheim the 

 uredospores also, in a favourable climate, can survive the winter. This is 

 certainly true in Australia, where (though the Puccinia is an introduced 

 one) the uredospores have been found the whole year round. In that 

 country the Coltsfoot does not exist, and the fungus is carried through 

 the winter by the uredo-stage ; in fact, according to McAlpine, it is most 

 common in the winter there. Arthur and Carleton say that the fungus 

 does the same as far north as Nebraska in North America, where the 

 Coltsfoot is only a naturalised plant. Uredospores were found alive in 

 every month of the year at Washington, D.C. 



In the Scottish Naturalist ('84, p. 270) this species is recorded for Poa 

 tin it, i i<x, but there may possibly be some error in this statement. Plow- 

 right says that the uredospores are not accompanied by paraphyses, 



