452 A MANUAL OF THE PENICILLIA 



consisting of the terminal axis and one, or occasionally two, more or less 

 appressed branches bearing metulae and sterigmata, with branches and 

 metulae commonly roughened (fig. 116B); branches variable in length, 15 

 to 30m by 3.0 to 3.5/i; metulae usually in groups of 2 to 3 or more, 10 to 

 15/1 by 3.0 to S.ofj., with apices slightly inflated; sterigmata usually in 

 clusters of 6 to 10, mostly 10 to 12^ by 2.5 to 3.0/x, occasionally up to 20/1 

 in length, not infrequently arising at different levels; conidia extremely 

 variable in size and shape, at first definitely elliptical, in age remaining so 

 or becoming ovate or subglobose; mostly 3.5 to 4.0/t in long axis, occasion- 

 ally up to 5.5 to 6.0/t, smooth- walled. 



Colonies on steep agar similar to those on Czapek but generally more 

 conspicuously floccose-funiculose (fig. 117D), usually heavier sporing and 

 aging more rapidly, often becoming olive-gray to mouse gray (R., PI. LI) 

 in 12 to 14 days; penicilli essentially as described above. 



Colonies on malt extract agar growing rapidly, usually covering the cul- 

 ture plate within 2 weeks, plane, loose-textured, with surface appearing 

 cottony in some strains, almost velvety in others, with funiculose habit 

 evident but not as pronounced as upon Czapek's solution or steep agars; 

 exudate not produced; penicilli as described above but generally more com- 

 pact, with elements usually shorter, and with conidiophores more con- 

 spicuously roughened. 



Species description based upon strains NRRL 933 (Thom 5034.8) and 

 NRRL 934 (Thom 5042.135), and duplicated by numerous additional 

 strains isolated from soil and other natural sources. This species is abun- 

 dant in nature and representative strains have been contributed by numer- 

 ous collaborators. Professor Raistrick included several strains among the 

 cultures sent from the Nobel Explosives Company in Ayreshire, Scotland; 

 other strains have come from sugar beet studies at Logan, Utah and else- 

 where. 



Thom (1930, pp. 270-272) considered Penicillium. terrestre Jensen to 

 represent one aspect of a complex of floccose-funiculose forms which he 

 grouped together as the P. gnseo-fidvum-terrestre series. Careful re- 

 evaluation of Biourge's discussion (1923, pp. 164-167) of P. griseo-Julvum 

 Dierckx, together with a thorough re-examination of two sub-cultures of a 

 strain derived from Biourge's culture and widely investigated under this 

 name, now leads us to regard this species as probably representing some 

 fasciculate form approximating P. urticae Bainier (see p. 536). Peni- 

 cillium terrestre, now considered as probably quite separate from P. griseo- 

 fulvum, shows marked variation in laboratory cultures. Different strains 

 range in texture from floccose, through funiculose, to almost fasciculate, 

 and vary in color from light yellow-green to rather dull blue- or gray-green. 



