ASYMMETRICA-VELUTINA 337 



Penicillium brevi-compactum series, marked particularly by the develop- 

 ment of uniisiiallj' compact penicilli in which all cellular elements are 

 closely compacted and appressed. Extension of the colony margin by 

 stolon development is characteristic of most forms on certain substrata. 



Page 

 Key to the Velutina 



I. Penicilli seldom branched below the level of metulae, with nietulae often 



more or less divergent P. citrinum series 338 



A. Metulae typically in verticils of 2 or 3, often unequal in length, conidial 



chains not forming well-defined columns; conidia elliptical to sub- 

 globose ; P . corylophilum Dierckx 341 



B. Metulae typically in verticils of 3 to 5, bearing crowded sterigmata and 



conidial chains usually in well-defined columns; conidia globose to sub- 

 globose. 



1. Colonies showing bright yellow to orange-pink shades in reverse; co- 



nidial areas in bright blue-green shades; usually producing citrinin. 



P. citrinum Thom 345 



2. Colonies showing dull yellow to olive buff shades in reverse; conidial 



areas in dull blue-green or yellow-green shades; not producing 

 citrinin P. steckii Zaleski 350 



C. Metulae tj'picallj- in verticils of 5 to 8, closely compacted; conidial chains 



not in well-defined columns P. paxilli Bainier 



(see P. brevi-compactum series) 

 II. Penicilli typically rebranched below the level of metulae, with main axes and 

 branches terminating in verticils of metulae. 

 A. Penicilli commonly long, with elements loosely arranged and often di- 

 vergent. 

 1. Conidiophores smooth-walled; colony margin not appearing arachnoid 

 (cobwebby). 



a. Colonies typically producing abundant yellow pigment in exudate 



and colony reverse; conidial chains often adherent into well-de- 

 fined columns; conidia less than 5^ in long axis; subglobose to 



elliptical P. chrysogenum series 355 



1'. Conidia elliptical, or occasionally subglobose. 



aa. Colonies usually showing abundant yellow exudate and yel- 

 low pigmentation in reverse P. chrysogenum Thom 359 



bb. (yolonies showing pale or colorless exudate, and vinaceous to 



brownish fawn colors in reverse.. P. meleagrinum Biourge 364 

 2'. Conidia globose to subglobose. 



aa. Colonies velvety, heavily sporing, in rich blue-green shades, 



often comparatively thin P. notatum Westling 367 



bb. Colonies loose-textured, flocculent, often lightly sporing, 



comparatively deep P. cyaneo-Julvum Biourge 371 



b. Colonies not producing yellow pigment in exudate or colony reverse; 



conidia commonly 5.0m or more in long axis, strongly elliptical. 

 1'. Conidia elliptical, fairly uniform in size; common in soil. 



P. oxalicum series 376 



