40 A Monograph of the Ervsipiiaceae 



tips of ultimate branches straight, blunt ; ascus globose, or sub- 

 globose, with a minute stalk, 45-50 x 40-48/^ ; spores 8, 20-24 



X ll-l$/Jt, 



*' This is a very distinct species. The branches at the tips of 

 the appendages are slightly curved, and diverge nearly at right 

 angles to the appendage. When mature, the plants often become 

 collected in entangled masses, giving the leaf the appearance of 

 being coated with dusty cobwebs'* (Peck, Reg. Rep. 25: 95). 



Host. — Hamamclis Virg iniana. 



Distribution. — North America : United States — Massachusetts, 

 Connecticut, New York, North Carolina, Ohio (71), Indiana, Ala- 

 bama (12), IlHnois, Wisconsin. Canada — Ontario. 



P. biuncinata is known at once by the long spreading colorless 

 appendages. The apex of the appendages is usually only once 

 forked, rarely the primary branches are again divided (see fig. 98). 

 I have once observed two asci in the same perithecium. 



4. P. LEUCOTRicHA (Ell. and Everh.) [Figs. 1 19-122] 



Sphaerothcca laicotricha Ell. and Everh. Joum. Mycol. 4:58. 

 1888; Sacc. Syll. Fung. 9: 365. 1891. 



5. viali Burr, in Ell. and Everh. N. Amer. Pyren. 6 (excl. 

 syn. Erysiphe mali Duby). 1892; Magnus, Bericht. Deutsch. 

 Bot. Gesell. 16; 333. //. 21. 1898; Grout, Bull. Torn Club, 

 26 : 374. //. j(5/. 1899. 



Albigo leucotricha (Ell. and Everh.) Kuntze, Revis. Gen. Plant. 

 3^• 442. 189 



Exsicc. : *Syd. Myc. March. 3161, sub 5. castagnei Lev. ; 

 Warlich, Parasit. Pilz. 17, 18, sub 5. castagnei Lev. (in Herb. 

 Hort. Imp. Petropol.). 



^Mycelium amphigenous, persistent, thin, effused; pcrithecia 

 densely gregarious, rarely more or less scattered, 75-96 // In di- 



ameter, subglobose or sometimes slightly pyriform, cells 10-16 ft 



,2 



wide, usually 10 fi; appendages of two kinds, one set springing 

 from the apex of the perithecium, the other inserted basally ; 

 apical appendages 3-1 1 in number, usually 3-5, more or less 

 widely spreading, or erecto-fasciculate, 4-7 times the diameter of 

 the perithecium, septate when young, becoming thick-walled, with 

 the lumen more or less obliterated, colored dark brown in the 

 lower half, paler towards the tip, apex undivided and blunt, or 

 rarely once or twice dichotomously divided ; basal appendages 



