Pezicula 347 



On Populus grandidentata and Popuhis tremuloides. 



Type locality: Ontario, Canada. 



Distribution: Known only from the type locality. 



Illustrations: Mycologia 31 : 457,/. /; 460,/. 2; 462, f. 3. 



This species is known from two collections by G. E. Thompson 

 and communicated by H. S. Jackson, University of Toronto, 

 Cryptogamic Herbarium 2054 and 2046. Said to cause canker 

 on living trees. 



The conidial stage is reported by Thompson as a Myxosporium 

 which forms definite cankers on young Populus branches. 



18. Pezicula purpurascens (Ellis & Ev.) Seaver, Mycologia 34: 

 414. 1942. (Plate 145.) 



Dermatea purpurascens Ellis & Ev. Jour. Myc. 4: 100. 1888. 

 Ascoconidium Castaneae Seaver, Mycologia 34: 414. 1942. 



Conidia found associated with this species and possibly repre- 

 senting its perfect stage. Ascoconidiophores club-shaped reach- 

 ing a length of 90 y. and a diameter of 12 y, pale-brown, each 

 containing one ascoconidium; ascoconidia broad-ellipsoid, reach- 

 ing a length of 30-40 n and a diameter of 9-10 ^i, borne on slender 

 stalk within the conidiophore, becoming disconnected, and 

 finally discharged through the ruptured conidiophore, 3-septate, 

 appearing brownish within the conidiophore but hyaline or 

 subhyaline when discharged. 



Apothecia scattered, erumpent, occurring singly, or two or 

 three crowded together, sessile, or subsessile, externally reddish- 

 purple, reaching a diameter of .75-1 mm.; hymenium plane, or 

 slightly concave, dirty-white, becoming reddish-purple but 

 lighter than the outside of the apothecium; asci cylindric- 

 clavate, reaching a length of 120-140 n and a diameter of 25-30 /i) 

 8-spored but some often undeveloped, 8-11 X 30-36 yu, hyaline 

 or nearly so, ellipsoid with the ends strongly narrowed, becoming 

 distinctly 3-septate, 9-1 1 X 30-36 m; paraphyses slender, slightly 

 enlarged above, reaching a diameter of 2-3 m, often slightly 

 colored. 



The exterior of the apothecium is clothed with a palisade of 

 appressed, poorly developed hairs which are dilutely purplish. 

 It is this character which has suggested the specific name. 



On dead limbs of chestnut, Castanea dentata. 



Type locality: West Chester, Pennsylvania. 



Distribution: Pennsylvania and Massachusetts. 



