574 A MANUAL OF THE PENICILLIA 



Emerson in 1945 from retting giiaynle shrub at Salinas, California. Be- 

 cause of its role in the retting process, Emerson has studied the species 

 quite exhaustively and has discovered an ascosporic stage which was un- 

 reported by the describers. 



Penicillium dwponti is assigned to the P. luteum series upon the bases of 

 its biverticillate penicilli with conspicuously lanceolate sterigmata bearing 

 strongly elliptical conidia and its perithecia with soft plectenchymatous 

 walls. 



The following emended description is based primarily upon notes fur- 

 nished by Emerson, supplemented to a limited degree by our own observa- 

 tions of his strain No. 26 (now maintained as NRRL 2155): 



Colonies on glucose-yeast agar growing rapidly at optimum temperatures 

 of 47° to 50°C., attaining a diameter of 7.0 to 8.0 cm. in 7 to 10 days; deU- 

 cately floccose, becoming somewhat mealy in older cultures, usually 1 mm. 

 or less deep, in age developing deeper tufts as overgrowths; variable in color 

 depending upon temperature, age, and other factors, at first white and 

 later developing dull shades of grayish green, lavender, or pinkish brown; 

 exudate irregularly produced, dark brown in color; reverse and agar pinkish 

 lavender or reddish brown. Mycelium branched, delicate, mostly 2.0 to 

 2.5 or 3.0m hi diameter. Conidiophores short, usually arising more or less 

 perpendicularly as lateral branches from the main hyphae, often simple 

 but not infrequently with 2, 3, or 4 irregular branches, septate, 5 to 30/i 

 in length by 2 to 3m diameter, slightly larger at the apex than at the base, 

 smooth -walled. Penicilli irregular (figs. 145A and B), varying from mono- 

 verticillate with 1 to 4 sterigmata at the apex of a short conidiophore, to 

 partially biverticillate, or fairly regularly biverticillate; metulae few in the 

 verticil, 5 to 7m by 2 to 3m; sterigmata acuminate, divergent, 8 to 10m by 2m. 

 Conidia in long tangled chains, readily separating from the sterigmata 

 without disjunctors, pale yellowish when mature, smooth, elliptical to 

 ovoid, 2 to 4.5m by 1.5 to 3.0m (fig- 145A). 



Perithecia not produced upon glucose-yeast agar but occurring regularly 

 and abundantly on moist, chopped guayule shrub in pure-culture rets 

 and occasionally on oatmeal agar cultures, at first white and cottony, 4 to 

 5 days at 45°C., then (7 days) pearl gray, soft, pliable and dehcately 

 leathery, with an external surface of fine interwoven hyphae; finally (14 

 days) pale grayish tan, up to 1 mm. or more in diameter (figs. 146A and B), 

 with a brittle or papery peridium which fractures fairly cleanly under 

 pressure, scattered or irregularly clustered but usually not confluent, sub- 

 globose, 0.4 to 1.3 mm. diameter; peridium indehiscent, plectenchymatous 

 (fig. 146C), the outer elements very small and compact, the inner becoming 

 larger (up to 10m diameter), less compact, and forming an almost pseudo- 

 parenchymatous tissue; asci very numerous, scattered, subglobose, 9-10m 

 diameter, 8-spored, disintegrating before the spores mature (fig. 145C); 



