MONOVERTICILLATA 127 



branching system. Westling and Thorn merely dropped the name Citro- 

 myces and called all of them species of Penicillium. 



Although the marks of division may be more or less unsatisfactory at 

 times, the individuality of each verticil of sterigmata with their conidial 

 chains is a character usually readily recognized when a growing culture in 

 a petri dish is viewed with low magnifications of the compound microscope. 

 For the purposes of our discussion, separation between the monoverticillate 

 group and the remainder of the Penicillia is based upon examination of the 

 terminal verticil of the main conidiophore. If there are no branches at the 

 apex of the main axis, or if each branch maintains fairly definite individual- 

 ity, i.e., produces a separate peniciUus, the species is assigned to the Mono- 

 verticillata. 



However, no sharp line of separation can be drawn between the Mono- 

 verticillata and either the Velutina or the Divaricata sub-sections of the 

 Asymmetrica. Complete bridging is effected between the Monoverticil- 

 lata and the Velutina through the Ramigena series and Penicillium corylo- 

 philuni in the P. citrinum series. A similar transition from the Mono- 

 verticillata to the Divaricata occurs through P. jenseni Zaleski. Additional 

 evidence of close relationship between the Monoverticillata and the Di- 

 varicata rests in the similarity of perithecia and sclerotia in the two sections. 

 A rigid separation into monoverticillate and biverticillate forms is thus 

 unattainable in fact, and one is led to recognize that the different sections 

 of the genus Penicillium are intimately related and represent merely differ- 

 ent facets of a large and variable group of molds. 



Key to the Monoverticillata 



I. Colonies producing perithecia or sclerotia. 



A. Colonies producing fertile perithecia, but perithecia often ripening late. 

 1. Perithecia firm or sclerotioid at first, ripening from the center outward. 



a. Penicilli monoverticillate or fragmentary P . javaniciim series 132 



1'. Colonies producing abundant red to reddish brown pigment 

 upon most substrata, 

 aa. Ascospores lenticular, about 2.5 to 3.0^ in long axis, with 

 equatorial ridges generally lacking and furrow often evi- 

 dent only as a line, with walls finely roughened 



P. javanicum van Beyma 135 

 bb. Ascospores lenticular, about 2.0m in long axis, with promi- 

 nent equatorial ridges and furrow, with walls roughened 



P. parvum Raper and Fennell 138 

 2'. Colonies not producing abundant reddish or reddish brown pig- 

 ment upon most substrata. 

 aa. Ascospores lenticular, about 3.0 to 3.5ju in long axis, with 

 furrow evident but not pronounced, with walls finely 

 echinulate; penicilli typically monoverticillate 



P. brefeldianum Dodge 141 



