476 A MANUAL OF THE PENICILLIA 



Penicilli variable in size but usually showing one or more branches in 

 addition to the main axis, terminating in metiilae and sterigmata and 

 bearing tangled chains of conidia. 



Colonies upon most media produce an earthy or moldy odor, often very 

 strong. 



Series Key 



1. Colonies lacking true green colors in areas of ripe conidia P. ochraceum series 



a. Conidial areas in yellowish olive, buffy olive or buffy brown shades. 



P. ochraceum (Bainier) Thorn 



b. Conidial areas in lighter shades near sandy brown or pinkish buff. 



P. carneo-lutescens Smith 

 0. Conidial areas colorless or in light cream shades. 



Color mutants of P. urticae and other species 



Two well marked species comprise this easily recognizable series, 

 namely: PeniciUium ochraceum (Bainier) Thom and P. carneo-lutescens 

 Smith. The former, as the name implies, is characterized by conidia that 

 superficially appear predominantly yellow-brown, although an olive colora- 

 tion is usually detectable when conidial areas are compared with reference 

 color charts. The latter species shows a lighter coloration, usually in 

 sandy to pinkish buff shades. The degree of relationship between the 

 species is not known, and they are considered together largely as a matter of 

 convenience. 



PeniciUium ochraceum commonly produces heavily sporulating colonies 

 which superficially appear deeply velvety or lanose. Largely in recog- 

 nition of this latter aspect Thom (1930) placed the species in his section 

 Lanata. Thorough comparative study of this species in relation to other 

 members of the Asymmetrica' that produce branched penicilli now con- 

 vinces us that it more properly belongs in the Fasciculata. Although 

 P. ochraceum is representative of a series based primarily upon the non- 

 green color of its conidia, attention should be called to the tendency for 

 this species to blend into the P. viridicatum series, next to be considered. 

 This probable relationship should not be overlooked, should any physi- 

 ological or biochemical study of either series assume importance. 



PeniciUium. carneo-lutescens Smith is allied to P. ochraceum primarily 

 upon the basis of spore color. Colonies are usually deeper and show a 

 more consistent and marked fasciculation. The species is regarded as 

 possibly based upon a non-green natural mutation of some cosmopolitan 

 species such as P. expansum. Link or P. corymbiferum Westling. Lacking 

 proof of such origin, the species is retained; nevertheless, natural muta- 

 tions with white to light tan or even pinkish conidia have been encountered 

 frequently enough to establish this possibility. 



