412 A MANUAL OF THE PENICILLIA 



Penicillium stoloniferum Thorn, in U. S. Dept. Agr., Bur. Anim. Ind., Bui. 

 118, 68-69, fig. 26. 1910. Thorn, The Penieillia, pp. 292-294, 



figs. 41 and 42. 1930 



Colonies on Czapek's solution agar (Col. PI. VI) growing restrictedly, 

 attaining a diameter of 2.0 to 2.5 cm. in 12 to 14 days at room temperature, 

 strongly wrinkled and buckled in most strains (fig. 107C), with central 

 areas often conspicuously raised and in age often splitting through the 

 underlying agar, typically consisting of a close-textured mycelial felt bearing 

 abundant conidial structures, with surface velvety to lanose in most strains 

 but more or less fioccose in others, usually azonate when young but com- 

 monly becoming narrowly zonate in age; conidial structures abundantly 

 produced throughout the whole colony but generally in greater abundance 

 in marginal to submarginal areas, typically in yellow-green shades approxi- 

 mating gnaphalium green to light celandine green (Ridgway, PI. XLVII) 

 when young to sage green or artemisia green (R., PI. XLVII) in mature 

 fruiting areas, and approaching stone gray (R., PI. LII) in age; limited 

 clear to pale yellow exudate produced in some strains, not in others; odor 

 neither pronounced nor distinctive; reverse dull yellow to gray or greenish 

 gray, with surrounding agar uncolored or lightly tinted in the same shades; 

 colony margins usually entire and compact during the growing period but 

 characterized by the presence of stolon-like aerial hyphae which re-enter 

 the substratum beyond the limits of the submerged vegetative mycelium 

 (fig. 107F). This development is especially pronounced in young colonies 

 on "wet" agar. PeniciUi typically short and compact with constituent 

 elements closely appressed, bearing parallel or divergent chains of conidia 

 (fig. IO6B1), and withal presenting the picture of a short, compact brush; 

 conidiophores arising either from the substratum, or as lateral branches 

 from aerial hyphae, the former ranging up to 250/x in length by 3.5 to 4.0m 

 in diameter, the latter from 35 to lOO/x by 3.0 to 3.5m, larger penicilli typi- 

 cally consisting of the main axis bearing a verticil of metulae and closely 

 compacted sterigmata and one, or occasionally more, side branches each 

 terminated by like spore bearing elements (fig. IO6B2), smaller penicilli 

 commonly show only a single terminal verticil of metulae surmounted by 

 crowded sterigmata; branches usually 10 to 25m by 3.0 to 3.5m, with sub- 

 branches occasionally evident; metulae parallel or slightly divergent, rang- 

 ing from 3 to 6 in number and varying from 8 to 12m by 2.8 to 3.8m; sterig- 

 mata borne in compact clusters of 4 to 8, not distinctive in form, with spore 

 bearing tubes comparatively short, generally measuring 8 to 10m by 2.2 to 

 2.8m; conidia elliptical when young but becoming globose to subglobose at 

 maturity, sometimes pyriform, finely roughened, usually 2.5 to 3.5m in 

 diameter. 



