348 UIIEDINEAE. 



])reseiit : ihe jmlisailL' layiT is (IouI)I(hI, and rupture of the 

 epidermis takes place ; chlorophyll-forniatiou is suppressed, the 

 cell-sap becomes yellow, and starch tends to accumulate. 



P. dispcrsa may cause serious damage to wheat and rye ; F. 

 rnhifjo-vcra, also on barley and oats. The spore-patches are 

 found on stalks and leaf-sheaths more than on the lamina. The 

 mycelium may hibernate in grasses, so that the fungus is not 

 dependent on the aecidial stage ; for this reason the disease is 

 not easily combated. 



P. glumarum Eriks. et Henn. Golden-rust. This species, 

 hilherlu generally included under P. rubifjo-vrra (D. C.) has been 

 separated by Eriksson and Henning.^ Experimental infection 

 on Boragineae gave negative results. 



Eriksson distinguishes the following specialized varieties of 

 this species : 



A. Definite (and undoubtedly distinct). 

 1. Var. trificl on Triticum vulgare. 



'1. \'ar. hon/ei on Hordenm vulgare (somewhat uncertain), 

 o. Var. (iijmi on Elymus arenarius. 



4. Var. a(jro}iyri on Triticum repens. 



B. Xot sharply defined : 



5. Var. stecalis on Sccalc errca/r. 



The uredospore-sori are lemon-yellow in colour, and form 

 lines on the leaf-blade which may run together and reach a 

 length of 10 mm. The teleutospore-sori form long, fine, brown 

 or black lines : the sori are divided into numerous chambers, 

 each enclosed in a circle of curved brown paraphyses. The 

 spores germinate in the autumn of the same year. The pro- 

 mycelium is yellow till tlie spores are abjointed : in this way 

 it is distinguished iVom P. ilispci'sa. 



P. poarum Xiels. (Britain). Uredo- and teleutospcjres on 

 /''/". According to Nielson, the aecidia occur on Tussilago, 

 Pda.sift's, and Adcnostylrs. Fentzling {lor. fit.) has described 

 certain anatomical changes which accompany deformations due 

 to the aecidia. 



P. phlei-pratensis Kriks. et Heun. Tliis lia.s a liil)tniiatiii<;- iiiycelium 

 wliifli produces uredospores I'ontinuoiisly on Phleum and inoliaUIy also 

 on Factum. Aecidia liave not as yet been observed. 



' Kiikssoii and Heniiiiig \loc. ri/.). 



