190 A MANUAL OF THE PENICILLIA 



monoverticillate forms. The series contains three well-marked species. 

 Penicillium lividum Westling is easily recognized by its deep velvety 

 colonies, its typical blue-green color, and its rough-walled, broadly eUipti- 

 cal to ovate conidia. Penicillium aurantio-violaceum Biourge presents much 

 the same cultural picture but differs markedly in producing strongly ellip- 

 tical conidia with ends usually somewhat pointed. Penicillium trzehinskii 

 Zaleski is characterized particularly by the production of colonies with 

 reverse in deep dull violet to fuscous shades. The series appears to be 

 closely related to the P. frequentans series through a P. trzehinskii to P. 

 spinulosum bridge (see p. 183). 



Penicillium lividum Westling, in Arkiv for Botanik 11: 58, 134-137, 



fig. 79. 1911. See also Dale, Ann. Mycol. 12: 52. 1914; and 



Thom, The Penicilha, pp. 205-206. 1930. 



Colonies on Czapek's solution agar growing fairly rapidly, approxi- 

 mately 3.0 to 3.5 cm. in 10 to 12 days at room temperature, hghtly fur- 

 rowed (fig. 52A), about 1 mm. deep, consisting of a tough basal felt with 

 loose surface growth, deeply velvety to almost lanose, azonate or nearly so, 

 at first white but showing blue to blue-green shades with the development 

 of abundant conidial structures after 6 to 8 days, ranging progressively 

 from glaucous gray to grayish blue-green (Ridgway, PI. XLVIII) to ap- 

 proximately deep olive to dark olive gray in age; exudate lacking; odor 

 wanting or indefinite; reverse at first uncolored, becoming dull peach to 

 flesh shades in age; conidiophores mostly single and arising from the sub- 

 stratum separately, usually unbranched but occasionally with a branch 

 somewhat below the tip, long, up to 400 to 600^ or more by 2.5 to 4.0/1 

 (fig. 52C), septate, smooth-walled or nearly so, swelling somewhat at the 

 apex and sometimes truly vesicular up to 5.0 to 6.0/x in diameter; penicillus 

 usually consisting of a single verticil of parallel or somewhat divergent 

 sterigmata bearing tangled conidial chains up to 50ju or more in length, 

 rarely forming loose columns; sterigmata mostly 5 to 10 in the verticil, 

 8 to 12/i by 2.0 to 3.0^, occasionally 15^ in length, with fairly conspicuous 

 spore-bearing tips (fig. 52D); conidia at first definitely elliptical, in age 

 usually becoming ovate to subglobose, mostly 3.0 to 4.0^ by 2.6 to 3.0ju, 

 with walls clearly roughened and commonly showing definite spiral band- 

 ing, especially in larger and more elliptical cells. 



Colonies on steep agar growing more rapidly, up to 5.0 to 5.5 cm. in 

 10 to 12 days, lightly furrowed or plane, with composition and texture as on 

 Czapek, deeply velvety or lanose with loose aerial growth 1 .0 mm. or more 

 deep (fig. 52B), medium to heavy sporing throughout except for a narrow, 

 white growing margin 1.0 to 2.5 mm. wide, conidial areas colored as on 

 Czapek; conidiophores arising almost exclusively from the substratum or 



