ASYMMETRICA-VELUTINA 



387 



textured but essentially velvety, plane, consisting of a well-developed vege- 

 tative mycelium at the agar surface upon which are borne abundant conidial 

 structures, margins essentially white, 2 to 4 mm. wide, and more or less 

 fimbriate in rapidly growing colonies, sporulating areas in dull yellow-green 

 shades near tea green and vetiver green (Ridgway, PI. XLVII) when young, 

 becoming grayish olive (R., PI. XLVI) in age; no exudate produced; odor 

 pronounced, strongly aromatic, suggestive of decaying citrus fruits or dill 

 as used in pickle manufacture; reverse uncolored or showing light to dull 

 brown shades. 



KM\\» ff 





A 



V 





Fig. 102. Penicillium digitatum Saccardo. Ai and A2, Details of penicilli showing 

 their characteristic irregular pattern, and cylindrical to strongly elliptical conidia 

 which are unusually variable in size, X 750. 



Colonies upon malt extract agar growing rapidly, attaining a diameter of 

 6 to 8 cm. in 10 to 14 days at 24°C., plane, velvety, closer-textured and 

 slightly heavier sporing than upon steep agar, but in general showing the 

 same cultural characteristics and coloration as upon that substrate; odor 

 pronounced, aromatic as on steep agar; reverse uncolored or in dull tan 

 shades; vegetative hyphae coarse, but consistently thin walled, varying in 

 diameter from 4.0 to 5.0m as a rule, but up to 8.0 to lO.O/x in occasional in- 

 stances; conidial structures characterized by great irregularity in the num- 

 ber and dimensions of parts (fig. 102), but usually consisting of an indefinite 

 number of branches and/or metulae supporting a limited but variable series 

 of spore-bearing cells or sterigmata, each terminating in a chain of conidia 



