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A MANUAL OF THE PENICILLIA 



fairly deep up to 1 to 2 mm. ])ut all characterized by loosely interwoven 

 and trailing liyphae bearing short conidiophores, sporulating over the 

 whole colony surface, marginal growth in some strains very thin, largely 

 submerged in zones from 1 to 3 mm. wide, colored in grayish yellow-green 

 shades near gnaphalium to tea green (Ridgway, PI. XLVII), in older 



Fig. 58. PenicilUum decumbens Thom, NRRL 742. A and B, Two-week-old col- 

 onies on Czapek and malt agars. C, Low-power view of colony margin showing 

 conidial structures borne as short branches from aerial and looping hyphae, X 100. 

 D, Detail of structure and origin of penicilli, X 900. 



colonies developing surface tufts of sterile secondary mycelium; exudate 

 lacking or inconspicuous; odor distinctive, fragrant, suggesting soap per- 

 fumes; reverse colorless or with a slight greenish cast; conidiophores 50 to 

 lOOju by 2.0 to 2.5ju, with apices slightly enlarged, smooth or finely rough- 

 ened, borne at successive nodes upon trailing hyphae (fig. 58C) which in 

 marginal areas of many strains grow stolon-like along the substratum; 



