Ervsiphe 221 



or lichenoid ; its color is usually white, but sometimes (as on Cap- 

 parts hcrbacca^ Clematis songaricd) it shows here and there patches 

 of a pale buff color, at these spots the mycelium somewhat re- 

 sembles thin washleather. Sometimes/however^ the myceliimi is 

 completely evanescent, as Leveillc, indeed, pointed out in 185 1. 

 We sometimes find on a plant whose leaves are for the most part 

 entirely covered with densely compacted persistent mycelium, 

 some leaves here and there on which there is no trace of mycelium, 

 the perithecia occurring quite naked on their surface ; also on 

 some plants which have a dense covering of stellate liairs on the 

 leaves (i\ g,, Verbascuni Blatiaria, V, plilonioides^ PJiloviis Hcrba- 

 vcnti) the mycelium is apparently never persistent. 



The persistent mycelium and large subimmersed perithecia 

 give to E. graniinis an external resemblance to the present species, 

 but E, taurica is most closely allied to E. cichoracearuui ; indeed, 

 occasionally certain forms of the latter species on Arctiuui show a 

 slight approach towards E, taurica. 



Komarow (206, p. 277) notes that in Seravschan (Turkestan) 

 at the height of 6,000 feet E, taurica is one of the 'most widely- 

 spread species, up to 4,000-5,000 feet, occurring on almost all the 

 plants of the steppes, but that higher than 6,000 feet the fungus 

 does not occur, although several of its hosts ascend to a higher 



altitude. 



E, taurica has been reported from Asiatic Siberia on Achillea 

 Ptarjnica, but the specimens I have seen from there all belong to 

 E. dehor acearitm. Leveille (214, p. 162) gives Cnicus eriopJiorus 

 as a host-plant for E. taurica^ but a specimen so named in Leveille's 

 handwriting in Montague's herbarium, on this host, is E, cichora- 



ccartivi. 



The conidia of E, taurica are very large ; in examples on 

 Euphorbia and Acanthophylluni they frequently measure 50 x 18 (u 



7. E. AGGREGATA (Peck) Farl. [Fig, 144] - 



Erysiphclla aggregata Feck, Reg. Rep. 28: 6"^. pL 2.f. i-j. 



1875 ; Sacc, Syll. Fung, i : 23. 1SS2. 



Erysiphe aggregata (Peck) FarL Bull. Buss. Instit. 2 : 227. 

 1878 ; Burr, Ell. and Everh. N. Amer. Pyren. 14. 1892. 



Exsicc. Seym. & Earle, Econ. Fung. 168; de Thuem. Myc. 



