142 THE AGARICACEAE OP MICHIGAN 



118. Russula atropurpurea Maire (ex. Kromb. non Pk.) 



Bull. Sco. Myc. de France, Vol. 26, p. 167, 1910. 

 Illustrations: Cooke, 111., PL 1025 and 1087 (as R. rubra). 



PILEUS 5-14 cm. broad, rigid, medium to large size, convex then 

 plane, soon depressed, rather firm, viscid, pellicle adnate and 

 scarcely separable on the margin only, scarlet to dark crimson when 

 fresh and young, 'becoming darker to purplish when mature or on 

 drying, pruinosc, disk often darker, sometimes blackish-red to livid 

 olivaceus-purple, sometimes yellow spotted, margin even or only 

 slightly striatulate in age. FLESH dark red under the pellicle, 

 white elsewhere, not changing to ashy. GILLS white, dingy in age, 

 rather narrow, close behind, subdistant in front, adnexed, few short, 

 interspaces venose. STEM 4.7 cm. long, 1-3 cm. thick, subequal, 

 medium stout, white with a dull lustre, pruinose, even, spongy- 

 stuffed, apex floccose-punctate. SPORES white in mass, oval, 8-10' 

 micr. diam., strongly echinulate, nucleate, apiculus long and stout. 

 TASTE acrid. ODOR none. 



Gregarious or solitary. On the ground, on much decayed logs 

 or debris, sometimes at base of white pine or beech trees, in pine- 

 beech woods. New Richmond. Sept. Frequent locally. 



Distinguished among the "ruber" group by the mode of color 

 change while maturing, the white gills, spores and stem, and the 

 acrid taste. In wet weather the cap is viscid, on drying its surface 

 is distinctly pruinose. Except for the colors of the pileus it agrees 

 with R. ruber Fr. in the sense of Peck. The stem is rarely inclined 

 to ashy in age but not distinctly so. According to Maire's concep- 

 tion the species is quite variable and includes plants whose stem- 

 readily turns ashy. 



SUBRIGIDAE. Pileus subrigid, rather compact; cuticle soon 

 dry, pruinose or prulnose-velvetij; margin obtuse. Gills broader in 

 front, equal. Spore-mass never pure white. 



This group approaches the preceding by its rather compact and 

 thick pileus, and the following by its equal gills. The pellicle is 

 soon dry and pruinose or pruinose- velvety by which character the 

 species are best recognized. Several aberrant species are, however,, 

 included, e. g., R. xerampelina with intermixed short gills and R^ 

 mariae with margin of pileus at first incurved. 



