MONOVERTICILLATA 



149 



(fig. 41 A), surface appearing almost velvety but consisting of a thin network 

 of short, closel}^ interwoven vegetative hyphae, white but gradually de- 

 veloping light buff to flesh shades in marginal areas, in age sometimes show- 

 ing even yellow and lilac zones, conidia limited, borne on very reduced 

 fruiting structures (see 20 per cent sugar-Czapek) commonly consisting of 



Fig. 41. Penicillium levitum Raper and Fennell, NRRL 705. A,B, and C, Colonies 

 on Czapek, malt, and corn meal agars, respectively. D, Ascospores, X 1500; note 

 smooth walls. See also fig. 14 showing ascosporic stage of this species. 



single sterigmatic cells, not influencing the colony appearance; perithecial 

 primordia present in limited numbers (see malt agar below), buried in the 

 mycelial felt, not developing mature asci or ascospores and not affecting 

 the colony appearance; exudate limited, clear; odor lacking; reverse in 

 yellow shades from citrine to dull buff. 



Colonies on Czapek's solution agar containing 20 per cent sucrose as 

 described above but developing conidial structures (fig. 42A) and perithecial 



