458 a manual of the penicillia 



Penicillium pallidum Series 

 Outstanding Characters 



Colonies spreading, usually rather thin, with surface growth somewhat 



funiculose; eonidia variable in color, white to cream, buff, light gray, 



or lavender to vinaceous — never developing true greens. 

 Conidiophores comparatively short, mostly arising from ropes of aerial 



hyphae; conspicuously septate, with walls of conidiophores, branches, 



and metulae closely and conspicuously roughened. 

 Penicilli usually comparatively narrow, with cellular elements tending to 



be closely appressed rather than divergent. 

 Sterigmata borne in compact clusters, closely parallel, comparatively 



thin, seldom exceeding 2.5ai in diameter, with walls often echinulate. 

 Conidia strongly elliptical to cylindrical, smooth -walled, often adherent in 



long chains in fluid mounts. 



Series Key 



A. Conidia white to cream colored. 



1. Conidial chains divergent, becoming tangled in age P. pallidum Smith 



2 Conidial chains in well-defined columns P. putterillii Thorn 



B. Conidia in light to dull gray shades P. namyslowskii Zaleski 



C. Conidia in light violet, lavender, or vinaceous shades. 



P. lavendulum Raper and Fennell 



The species included here may or may not represent a natural series. 

 All of them, however, possess certain marked characteristics in common 

 which enable them to be considered together more satisfactorily than with 

 any other recognized forms. Irrespective of their true relationship, the 

 general pattern of the penicillus is much the same in all cases (fig. 119). 

 This is likewise true of the character of conidiophore walls and the dis- 

 tinctive form of conidia. 



The four species included may be separated as shown in the above key, 

 and may be further characterized as follows: Penicillium 'pallidum Smith 

 shows a complete lack of color in young conidial areas but tends to develop 

 light cream shades in age. Conidiophores are usually quite short, con- 

 spicuously septate, and often arise from cellular elements in the parent 

 hyphae that are strongly suggestive of the foot-cells of Aspergillus. The 

 same is seen to a lesser degree in other members of the series. Penicillium 

 putterillii Thom, as originally described, differs from the above primarily 

 in producing colonies in darker shades, approaching avellaneous. Peni- 

 cillium namyslowskii Zaleski is distinguished by its very sparse, spreading 

 colonies on Czapek agar, coupled with the production of dirty white to 

 very light gray conidial masses and the development of a very strong pene- 

 trating earthy odor on all substrata. Penicillium lavendulum Raper and 



