Erysiphe 193 



coat of the host." Burrill (60), in his description of E, cichora- 

 cearum says : '* Sporidia large, quite uniformly 2, but occasionalh' 

 varying to 3 or even 4" (on Bigclovia 5 or 6), and, under the same 

 species, adds the further remarks, *' A form on Bigclovia gravco- 

 lens has 20-30 asci, many of which have 3-5, and perhaps more, 

 sporidia, and the appendages are short and ahnost hyahne. Taken 

 by itself, it could hardly be admitted as belonging to the present 

 species, Ellis and Everhart provisionally propose the name E. 

 scpulta for it. But on Bigclovia Douglasii, growing with the pre- 

 ceding, the fungus is in all characteristics the same, except that 

 the sporidia are uniformly 2, in the specimens examined, and so re- 

 ported by others. The asci are often as many as 30 in both cases, 

 a number much greater than commonly given for t>^pical E, 

 dehor accarum. On other host species the number of asci is ex- 

 ceedingly variable, mostly only 4-S, but in some collections east 

 of the Mississippi river reaching 20, with apparently no way of 

 distinguishing different species among the variable forms. Those 

 on Bisrelovia are indeed further aberrant, but it does not seem 



'i> 



wise to separate one or both as specifically distinct, either from 

 each other, or from those with which they are undoubtedly allied 

 on the host-plants enumerated above." 



Jones (179), in " E. cidioraccarum'' on Bigclcnia gravcolcns 

 from Utah, remarks; "asci numerous, 15-20 or more; sporidia 

 uniformly 4-6, much smaller than in the type. . . The characters 

 given above would suggest a relationship to E. communis rather 

 than to E. dehor ace arum, but no forms of that species have so far 



been reported on Compositae." 



It may, however, be pointed out that, among Compositae, a 

 form of E. polygoni occurs on the stem of species of Carduus and 

 Cnicus, which although very unlike the var. scpulta in its small 

 size, yet approaches it in possessing numerous asci (23 or more). 

 The form of E. polygoni described as E. vernalis, also, must 

 be considered in dealing with the question of the position of the 

 present plant. 



2. E. CICHORACEARUM DC. [FigS. I40, I51] 



Muc or Erysiphe Leyss. Fl. Hal. 305. 1783. 



Erysiphe cichoraccarnm DC Fl. Fr. 2: 274. 1805; Wint. ; 



