BIVERTICILLATA-SYMMETRICA 651 



Penicillium tardurn Thom, in The Penicillia, pp. 485-487, fig. 84. 1930. 

 Synonym: Penicillium elongatum Bainier, in Bui. Soc. Mj^col. France 

 23: 17-18; PI. V, figs. 1-7. 1907. 



Colonies upon Czapek's solution agar growing very restrictedly, attaining 

 a diameter of 1.5 to 2.0 cm. (fig. 164E) in 12 to 14 days at room tempera- 

 ture, usually with central areas raised, 1 to 2 mm. deep, floccose-funiculose, 

 at first white but developing dull gray-green shades with the production of 

 conidial structures, with marginal zone very thin, largely submerged, 2 to 

 4 mm. wide; in some strains with entire colony consisting of a very thin 

 submerged mycelium producing scattered conidial structures usually more 

 concentrated in central areas, irregularly gray -green to dark yellow-green 

 in color from a limited production of conidial structures; odor hmited or 

 indistinct; exudate lacking; reverse uncolored to fairly bright yellow at 

 colony centers, with green of conidial structures often showing through in 

 marginal areas; penicilli typically biverticillate-symmetrical but often frac- 

 tional, bearing conidia in long tangled or loosely parallel chains; conidio- 

 phores arising either from the substratum or from aerial hyphae, variable 

 in length, commonly lOOju or less by 2.0 to 2.5m in diameter, but occasion- 

 ally up to 303 to iOOfjL long, smooth-walled ; metulae in verticils of 5 or more 

 in larger penicilli, mostly 9 to 12/x by 2.0 to 2.5m; sterigmata closely parallel, 

 in verticils of 5 to 7 or 8, lanceolate, typical of the group, mostly 8 to lO/x 

 by 1.8 to 2.2m, occasionally longer with long tapered conidium-bearing 

 tubes; conidia elliptical, rarely subglobose, mostly 3.0 to 3.5m by 2.0 to 2.5m 

 with walls comparatively heavy and somewhat roughened, dull olive-green 

 in mass. 



Colonies on steep agar as described above but quickly developing dull 

 olive-gray shades with thin marginal zone often less conspicuous and tend- 

 ing to develop a limited floccose growth in age; reverse uncolored or showing 

 drab to dull reddish shades; conidial structures as described above. 



Colonies on malt agar growing more rapidly, about 3.0 to 3.5 cm. in two 

 weeks, variable in pattern and texture depending upon the individual 

 strain, in some tending to be floccose (fig. 164F) up to 2 mm. or more deep 

 and sporulating irregularly to give the culture a zonate to mottled appear- 

 ance, conidial areas in dull ])lue-green shades; in other strains colonies are 

 less floccose, velvety or nearly so, heavier-sporing, in shades near sage 

 green (R., PI. XLVII), reverse in dirty cream to dull orange-brown shades; 

 penicilli as described above. 



Species description centered upon NRRL 1073, cited by Thom as one 

 of the types (his No. 4640.444), and NRRL 2116 received from the Cen- 

 traalbureau in July 1946, listed as having come from Thom in 1937 as 



