382 A MANUAL OF THE PENICILLIA 



ment of young spore-bearing structures, fruiting areas light bluish green 

 at first but soon becoming sage green (Ridgway, PI. XLVII) to Russian 

 green (R., PI. XL II) and eventually dark olive in age, usually azonate but 

 at times broadly and indistinctly zonate; reverse in deep orange-red to 

 mahogany shades in colony centers, shading through lighter tints of the 

 same shades toward the margin; odor slight, not distinctive; conidial struc- 

 tures abundant, arising primarily from the substratum, less commonly from 

 surface hyphae, usually appearing as a close and regular stand of erect 

 fructifications; penicilli asymmetrical, 25 to 40m in length, showing con- 

 siderable irregularity in size and pattern (fig. QQBo), in most cases consisting 

 of a terminal verticil of 2 to 4, more or less, divergent metulae, in others 

 branched with one or more metulae borne upon each branch in addition 

 to the terminal stem, in scattered instances appearing monoverticillate, 



A B 



Fig. 101. Penicillium atramentosum Thorn, NRRL 795. .-1 and B, Two-week old 

 colonies on Czapek and malt agars. 



chains of conidia adhering into poorly defined columns (fig. 99Bi), or more 

 divergent and becoming tangled with those of adjacent heads, commonly 

 50 to 75m in length, rarely more than 100m; conidiophores very irregular in 

 length, commonly 50 to 75m but ranging from 25 to 125m, mostly 2.5 to 3.5m 

 in diameter, with all walls smooth; branches when present 8.0 to 15.0m by 

 2.5 to 3.0m; metulae 8.0 to 13.0m by 2.2 to 2.8m; sterigmata in verticils of 

 2 to 6, somewhat variable in form, mostly 8.0 to 12.0m by 2.0 to 2.8m; 

 conidia mostly elliptical, less commonly subglobose 3.0 to 4.0m by 2.8 to 

 3.5m, smooth-walled (fig. 99B3). 



Colonies on steep agar growing somewhat more rapidly than on Czapek, 

 more closely and conspicuously furrowed but like the above in texture and 

 general coloration, and producing similar penicilli. 



Colonies upon malt extract agar 5.0 to 6.0 cm. in diameter in 10 days at 

 room temperature, plane, velvety, azonate, heavily sporulating (fig. lOlB), 



