Uncinula 79 



nor to suppose that any intimate connection exists between the 

 fungus and the mite. I have once seen Uncinula circiitata on 

 "erineum" galls on the leaves of Acer rubnini, and in this 

 instance the unusual habitat had no observable effect on tlie 

 fungus. Halstead (156) records the occurrence of '' Sphacrothcca 

 pruinosa'' on P//;'/^////^ distortions on the inflorescence o{ Rhus 

 glabra. All these cases, however, differ from that of S, 

 phytoptopJula in one important respect, viz., that the species of 

 fungi recorded are found commonly on tlie same host-plant when 

 this is not attacked by mites, while S. phytoptophila (or any species 

 of SpJiaerothccd) has not been recorded from Cclds unless this 

 host-plant has been altered by the attacks of the Fhytoptns, 



Anderson and Kelsey (7) mention an association with mites of 

 " S. Castagnei'' on Shepherdia argcufca, Rnd of S, uiors-nvac on Ribcs 

 rotundifoUiun, stati] 



abnormally developed buds, and thickened brittle upper leaves 

 bore the perithecia of largest size and in greatest numbers," In- 

 stances are also given of mites occurring with *' ^. CastagncV on 

 Geranium incistun^ with Erysiphe coniinunis on Oxytropis Lanibcrti^ 

 Astragalus triphyllus, and A, adsurgens^ and with E, cichora- 

 cearuni on Chrysopsis villosa, Hi 



fc> 



Hanthiis (several species), Cnicus 

 undulatus^ Erigeron inacranthus and Mertcnsia Sibirica, In all 

 these cases, however, we may note that the fungus in question 

 occurs commonly on unattached parts of the host-plant mentioned, 

 and in many cases it is very probable that the presence of the 

 mites is merely a coincidence. 



UNCINULA Lev. Ann. Sci. Nat. IIL 15: 151. 1851 



Perithecia globose to globose-depressed ; asci several, 2-8 



spored; appendages simple, or rarely {U. accris) once or twice 

 dichotomously forked, uncinate at the apex, usually colorless, 

 rarely dark brown at base or throughout Etym.: dim. of uncus. 



Distribution. — Europe, Africa, Asia, Australia, North and 

 South America — 18 species and 2 varieties. 



The genus is distinguished at once by the uncinate apex of the 

 appendac[es. 



Key to ttae Species of the Genus I'liciiiula 



I. Appendages colored. 

 Appendages colorless. 



2, 



3- 



