BIVERTICILLATA-SYMMETRICA 607 



Gymnoascus; and among the ascosporic Penicillia, they are most nearly ap- 

 proximated in P. wortmanni and alhed members of the P. luteum series. 

 The ascospores are unusually large, and show a unique type of ornamenta- 

 tion. Conidial structures vary in complexity from strictly monoverticil- 

 liite, composed of terminal verticils of sterigmata numbering up to 5 or 6 or 

 occasionally more, to variously branched and biverticillate, but never show 

 either the characteristic symmetric pattern of the P. luteum series or the 

 bng tapered sterigmata that characterize the whole Biverticillata-Sym- 

 metrica section. Despite the basic differences shown by its conidial stage, 

 the species is tentatively placed in the P. luteum series with other species 

 producing perithecia without walls of definitely specialized cells. More 

 exact placement must await a thorough and detailed examination of the 

 developmental history of the species, or the isolation of additional strains 

 transitional between it and other well defined species. For the convenience 

 of the user of the Manual, the species is keyed with the ascosporic species 

 of the Monoverticillata as well as members of the Biverticillata-Symmetrica 

 that produce perithecia without definite cellular walls. 



Occurrence and Significance 



Members of the PeniciUium luteum. series are principally of soil origin 

 but also occur upon many organic materials undergoing slow aerobic de- 

 composition. Some species, notably P. vermiculatum Dangeard and P. 

 wortmanni Klocker, appear to be especially abundant in nature and in our 

 experience have been obtained from sources world-wide in origin. They 

 were commonly encountered among the molds isolated from military equip- 

 ment, including canvas and other fabrics, optical instruments, leather 

 goods, etc. undergoing deterioration in tropical and subtropical areas. 

 Other species such as P. aveUaneum Thom and Turesson, P. spiculisporum 

 Lehman, and P. stipitatum Thom, occur less frequently but are apparently 

 similarly distributed. A few species, such as P. haciUosporum Swift, 

 P. helicum Raper and Fennell, and P. rotundum of the same authors, are 

 known only as the type strains. PeniciUium luteum Zukal in its typical 

 form is apparently rare, for it appears to have been isolated only three or 

 four times since Zukal described it about sixty years ago. PeniciUium 

 striatum Raper and Fennell was first isolated from canned blueberries, but 

 it has since been obtained from soil also. The latter is believed to represent 

 its natural habitat. 



The name PeniciUium luteum has been used rather loosely to include 

 various members of the Biverticillata-Symmetrica which produce colonies 

 showing considerable yellow mycelium, with or without attendant peri- 

 thecium formation. Hence, it is frequently impossible to know the true 



