72 A MOXOGRAPII OF THE ErYSIPHACEAE 



been occasionally confused in America) in the dark-brown color 

 of the persistent mycelium, the usually smaller ascus, etc. 



In 1865 Otth (262) described a species of Sphaerothcca on the 

 leaves and stems of Euphorbia dulcis in Switzerland, under the 

 name of '' Erysiphc {Sphaerotheca) tomentosa;' with the following 

 description; " Epiphylla caulinaque. Subiculum maculaeformi- 

 effusum, tomentosum, rufum, in ambitu albidum, e floccis longis- 

 simis, rufis, eseptatis, contextum. Conceptacula subiculo inspersa, 

 subimmersa vel plus minus emersa. Appendiculae a subiculi 

 floccis minime distinctae. Sporangium unicum, sporis octonis 

 foetum." In 1877 the same plant was published as a new species 

 under the name o{ Erysiphc gigantasca by Sorokin and dc Thuemen 

 (in de Thuemen's Myc. Univ., no. 654) on the stems oi Euphorbia 

 phxtyphyllos and E. diilcis in Russia. In 1881 Baumler (20*) 

 recognizing that Sorokin and Thuemen's plant was a Sphaerothcca, 

 called \t S. gigantasca. Jaczewski in 1896 revived the forgotten 

 name of Otth's 5. tomcntosa. 



An earlier name, however, for this plant on Euphorbia is that 

 of Botrytris cuphorbiae, published by Castagne (67) in 185 I for a 

 fungus on Euphorbia Pcplus. The identity is pointed out by M. 

 Hariot in a note attached to a specimen of " Botrytris cuphorbiae 

 Cast" in the herbarium of the Paris museum, in which it is stated 

 that in this author's opinion the fungus is " ^rj'^////.' ^/V^///,r^r^ 

 Sorok. & Thuem." The specimen is very young, and the mycelium 

 has not yet attained its characteristic brown color, but I was able 

 to find a few perithecia, showing a single ascus, and there can be 

 no doubt that the Batrytis cuphorbiae of Castagne is the same 

 fungus as Otth's Sphaerothcca tomcntosa. 



Although the specific validity of this European fungus on 

 Euphorbia has not hitherto been questioned, it appears to me that 

 it cannot be separated from 5. mors-uvae. After much comparison 

 I have failed to find sufficient characters to separate this European 

 plant on Euphorbia from the American one on Ribes. Although 

 as a rule the fungus on Euphorbia affects the stems rather than the 

 leaves, there are specimens in Otth's herbarium, noted as "forma 

 epiphylla," in which it forms irregular pannosc or felted patches 

 on the leaves, exactly resembling those of S. mors-uvae on the 

 fruit of American gooseberries. The dark brown hyphae of the 



