BIVERTICILLATA-SYMMETRICA 565 



of equatorial markings, commonly spinulose over their entire surface 

 but in certain species pitted or distinctively banded; in occasional mem- 

 bers lenticular showing a prominent equatorial zone. 



Colonies spreading broadly in some species, in others growing more re- 

 strictedly; usually close-textured on Czapek's agar and often developing 

 perithecia late and in Hmited numbers only; growing more luxuriantly 

 on malt agar and typically developing abundant perithecia which im- 

 part to these molds their characteristic j^ellow coloration, approximating 

 luteus of Saccardo. 



Penicilli abundantly produced in some strains, not in others; typically 

 biverticillate and symmetrical but with monoverticillate or fractional 

 structures often predominating in individual species and strains. 



Sterigmata typically lanceolate or acuminate, i.e., comparatively long and 

 tapered in the manner characteristic of the Biverticillata-SjTnmetrica 

 section. Conidia typically but not uniformly elliptical, with ends 

 usually pointed and walls smooth; mostly in pale blue-green to gray- 

 green shades. 



Series Key 

 (See General Key to Biverticillata-Symmetrica) 



This series includes some of the most colorful and most interesting mem- 

 bers of the genus Penicillium. All are characterized by the production 

 of perithecia, usually in abundance, which are surrounded by loose mantles 

 or wefts of coarse, encrusted hj-phae. In the majority of forms, this en- 

 veloping mycelium is highly pigmented in yellow to golden or orange- 

 yellow shades and it is this aerial growth which imparts to the colonies their 

 characteristic coloration. 



Penicilli may be regarded as typically biverticillately-SATnmetrical, al- 

 though many members seldom develop structures of this tj-pical pattern. 

 Simple monoverticillate structures predominate in some strains and species, 

 asjTnmetric structures of varying complexity are most common in others, 

 but in most species the penicilli are symmetrical and biverticillate, hence 

 wholly typical of the section to which the series is assigned. Irrespective 

 of the complexity of the conidial apparatus developed, the ultimate coni- 

 dium bearing cells, or sterigmata (except in Petiicillium avellaneum and 

 P. striatum), are consistently lanceolate or acuminate and thus afford a 

 reliable index of relationship. 



The perithecia differ markedly from those of the Penicillium javanicmn 

 and the Carpenteles series already considered (see p. 132 and p. 260). Un- 

 like the above, which are characterized by definite peridia composed of one 

 to many layers of compacted thick-walled cells, the perithecia of the P. 

 luteum series typically show no definite walls and are bounded only by net- 



