BIVERTICILLATA-SYMMETRICA 561 



Key to the Birerticillata-Si/mnirtricn 



Page 

 I. Colonies typically producing perithecia or sclerotia. 



A. Colonies producing soft perithecia upon most substrata, usually in bright 



yellow (luteus) shades P- luteum series 564 



1. Ascospores usually with prominent equatorial ridges. 



a. Strains typically thermophilic; colonies pale salmon colored to dull 



grayish green . . P . duponti Gn^on and Maublanc emend. Emerson 573 



b. Strains not thermophilic; colonies typically bright yellow to green- 



ish yellow P- stipilatum Thorn 577 



2. Ascospores without definite equatorial ridges. 



a. Ascospore spinulose over their entire surface; asci borne in chains. 

 1'. Ascospores elliptical. 



aa. Perithecia in bright yellow, golden yellow or orange-yellow 

 shades. 

 1". Ascospores 4.0 to 5.0m in long axis. 



aaa. Perithecial initials enlarged, long, clavate, un- 

 branched; colonies spreading broadly. 



P. vermiculatum Dangeard 580 

 bbb. Perithecial initials irregularly enlarged, septate 

 and often branched; colonies somewhat re- 

 stricted P- wortmanni Klocker 583 



2". Ascospores seldom exceeding 3.0m in long axis; peri- 

 thecial initials long, helicoid; colonies spreading 



broadly P- helicum Paper and Fennell 586 



bb. Perithecia in white to cream or light yellowish shades; peri- 

 thecial initials conspicuously swollen, often becoming 



branched P- spiculisporum Lehman 589 



2'. Ascospores globose. 



aa. Conidia elliptical with ends somewhat pointed; perithecia 

 in golden-yellow to orange-yellow shades. 



P. rotundum Raper and Fennell 591 

 bb. Conidia bacilliform, rod-like; perithecia typically in pale 



yellow shades P- bacillosporum Swift 594 



b. Ascospores not spinulose over their entire surface; asci borne singly 



as short branches from fertile hyphae. 

 1'. Ascospores with walls pitted; perithecia in bright yellow shades; 

 conidial heads in avellaneous shades. 



P. avellaneum Thorn and Turesson 597 



Fig 143. Conidial structures in different members of the PenicilUum luteum series. 

 Ai, Habit sketches of penicilli in P. stipitatum Thom; A2, Camera lucida drawings 

 showing the irregular pattern and apparently fractional character of penicilli of the 

 same species. J5i, Habit sketches of penicilli in P. wortmanni Klocker; Bo, Detailed 

 drawings of the same, showing the symmetrically-biverticillate character of penicilli 

 and the lanceolate pattern of sterigmata which together characterize the Biverticil- 

 lata-Symmetrica. Ci, Penicilli of P. avellaneum Thom and Turesson as seen under 

 low power; d. Camera lucida drawings showing the pattern and cellular arrange- 

 ments in penicilli of the same species. Neither the general pattern of the^pemcillus 

 nor the character of the sterigmata in the latter species are typical of the section, 

 but the ascosporic stage is regarded as placing P. avellaneum in the Biverticillata- 

 Symmetrica. 



