10 



On Quercus ayrjfolia, California (Harkness). 



A very distinct and characteristic species. The filaments of 

 the mycelium are exceedingly robust, forming a dense, coherent 

 stratum. The perithecia are imbedded in this wooly mass, but when 

 carefully separated appear to be absolutely without appendages. 

 The thick threads of the mycelium do not adhere to the perithecia 

 when thus transferred to a microscopic slide. 



ERYSIPHE, (Hedw.) 



Lev. Ann. Sci. Nat. Ser. Ill, Tome XV. 



Perithecium containing several asci. Appendages simple, threads 

 similar to and frequently interwoven with the mycelium. 



E. Liriolendri, Schw. Syn. N. Am. p. 209. 



On leaves and succulent stems. Mycelium abundant, dense, 

 white, persistent. Perithecia developing late, mostly after the leaves 

 have fallen, rather large, 100 fj. or more, delicate, thin-walled, im- 

 bedded in and partially covered by the dense mycelium, reticulations 

 small and indistinct; appendages several, hyaline, rather long, much 

 interwoven with the mycelium. Asci several, eight or more. Sporidia 

 6-8, small. 



On Liriodendron tuUpifera, New York (Peck) to Illinois and 

 probably westward. The species is not uncommon on the host named, 

 though it appears to be slow in fruiting. May be identified by its 

 abundant, white mycelium, especially on the young stems. 



E. communis, (Wallr.) 



A Iphilomarpha communis, honidula, Wallr. in part, Verhandl. Naturf. Freund. I. 



Erysibe communis, nitida, Rabh. Deutschl. Krypt. Flora. 



Erysibe communis, I,k. in part. 



Erysiphe Aquilegia, DC. Flore Franc. VI, p. 105. 



Erysiphe Pisi, DC. 1. c. II, p. 274. 



Erysiphe Convolvuli, DC. 1. c. II, p. 274. 



Erysiphe Polygoni, DC. 1. c. II, p. 273. 



Erysiphe communis, Fr. Summa Veg. Scand. p. 406. 



Erysiphe communis, Martii, Lev. in part, Ann. Sci. Nat. Ser. Ill, Tome XV. 



Amphigenous. Jlycelium abundant, persistent or sometimes 

 evanescent. Perithecia variable in size and reticulations; appendages 

 variable in length, often long, lying on the mycelium or more or less 

 interwoven with it, usually colored in part or throughout, but occasion- 

 ally all hyaline, sometimes branched. Asci 4-8, or more. Sporidia 

 mostly 4-8, variable in size. 



Very common from ocean to ocean on a very large number of 

 host plants, among which are the following ; Clematis Vu-ghiiana, 

 C. ligusticifnlia, Anemone Virginiana, Anemonella thcdictroides, 



