12 A Monograph of the Erysiphaceae 



name Sclerotiiim Erysiphe to Linnaeus' species, and in iSoi (Syn. 

 Meth. Fung, i: 1 24) separated the plant on Corylus as van 



corylea {= Phyllactinia coryled). 



In 1804, in a work by Rebentisch (295) we meet with the first 

 illustration. The fungus was called Sclerotiiim sitffultiun, and 



F 



represents the species now known as Phyllactinia corylea. 



In 1805 De CandoIle(62) published the mss. genus '^Erysiphe 

 Hedw- f./' and very briefly described, often under several different 

 names depending on the host-plant, the species now known as 

 Phyllactiuia corylea^ Uncinula salicis, Erysiphe polygenic E, cicho- 

 raceantni^ and Microsphaera bcrheridis, De Candolle in 1806, in 

 the' Syn. PL Gall, added Erysiphe aceris (= Uncimda aceris) ; in 

 1807 (64) E. oxyacanthae {~ Podosphaera oxyacanthae), and in 

 181 5, in vol. 6 of the Flore Frangaise the species now called Micro- 

 sphaera etionyud, M. astragali, M, aba var. lonicerae, SphaerotJicca 

 htOHuli, Uncinula prnnastri, Erysiphe grandnis and E. galeopsidis. 

 In i8i5,also, Bivoni Bernardi (41) described and figured Ery- 

 siphe vagans (= Phyllactinia corylea^ and E. clandestiiia {=Unci' 

 nula clandestina^. The figures of both are good, and in that of the 

 latter species the uncinate apex of the appendages is carefully shown. 

 In the same year Fries in Obs, Myc. p. 206, united al! the 

 hitherto described species under the name of Erysiphe varium. 



The alteration of the spelling of the genus to '^ Erysibe'' orig- 

 inated with Nees von Esenbeck, in 18 17 (257), who used the 

 name " Erysibe stiff idtiini Rebent." for the Erysiphe stiff ultiun of 

 that author, and subsequent authors followed in attributing the 

 word ^^ Erysibe'' to Rebentisch. 



In 18 19 the most important of the early w^orks on the Ery- 

 siphaceae appeared. These were Wallroth's two papers, one en- 

 titled '' Naturgeschichte des Mucor Erysiphe^ in the Berlin GeselL 

 Nat Freunde Verhandl. i ; 6-45 ; the other, called *' De Miicore 

 Erysiphe Linnaei observationes," in the Annah Wett. Gesell. 4 : 

 226-347- 



Through Wallroth's work an important addition was made to 

 the existing knowledge of the family. It may be said that in all 

 works prior to this date the host-plant on which the Erysiphe grew 

 afforded the chief specific character. Wallroth pointed out that 

 the same species often grew on a great number of different host- 



