154 A Monograph of the Erysiphaceae 



M. calocladopJiom Atkins. Journ. Elisha Mitch. Sci. Soc. 7 : 73 

 (cum icon.). 1891 ; Burr, in Ell. & Everh. N. Amer. Pyren. 29. 

 1892; Sacc. Syll. Fung, i : 253. 1895. 



Exsicc: *Seym. & Earle, Econ. Fung. 179; Rab.-Wint. 

 Fung. Eur. 3538; Ell. & Everh. N. Amer. Fung., sec. ser. 1538; 

 Rav^ Fung. Amer. Exsicc. 625, sub M. extoisa. 



Main axis of many of the appendages not dividing dichotomously 

 at the apex, but growing on and bearing sets of opposite branches, 

 which occasionally show the same axial elongation ; asci 62-75 

 >< 42-45 /^; spores large, 24-28 x 1 2- 1 5 //. 



1 



■^ Var. ludens var. no v. [Figs. 27-3 c 



Perithecia more or less densely gregarious ; appendages nu- 

 merous, often crowded, about i ^ times the diameter of the peri- 

 thecium, usually flexuose-contorted or angularly bent, apex usually 

 very irregularly and widely branched, 4-5 times dichotomous, pri- 

 mary branches usually rather long, and those of the subsequent 

 orders unequal and irregularly placed, with the tips straight ; some- 

 times the branching is closer and more regular, with the tips dis- 

 tinctly recurved ; asci and spores as in 3f. aim. 



Hosts. — Vicia Americana and vars. linearis and trimcata. 



Distribution. —-^o^T^ America: United States— South Da- 

 kota (Brookings (D. Griffiths, Aug. 1 892) and Snoma (Griffiths 

 and Carter, Aug. 1897)), Wyoming (French Creek, Williams and 

 Griffiths, Aug. 1898). 



Among the duplicate specimens (now in the Kew Herbarium) 

 sent to me from the fine collection of Erysiphaceae made by Grif- 

 fiths in Dakota, Wyoming and Montana there are examples of a 

 ^ha■osphacra,_gxo^^■m^ on the species of Vicia named above, which 

 are very difficult to place. 



/^ 



Hf. 



diff^ 



at my disposal, and to compare them with the present plant. 



From all specimens seen of M. diffusa Griffiths' plant differs 

 m possessing, frequently, a recurved tip to the ultimate branches. 

 Sometimes we find a single appendage with the tips all regularly 

 and distinctly recurved, and the mode of branching of the whole 

 apex not very unlike that of M. aim, and certainly like that of 

 some of its varieties, e. g., var. divaricata (Figs. 28, 30). On the 

 other hand a large proportion of the appendages show an apical 



