CLASSIFICATION OP AGARICS 135 



cm. loug, 1-1.5 cui. thick, subeqiial or irregularly enlarged, rigid- 

 fragile, surface at the very tirst covered by a sulphur-yellow pul- 

 verulence, at length dotted hg sulphur-yellow granules, cspcviaUg 

 at base, white beneath, spongy-stuffed, becoming cavenmus. 

 SPORES globose, echinulate, 6-8 micr. (incl. apiculus), tvhite in 

 mass. CYSTIDIA numerous, subhymenium scarcely differentiated. 

 BASIDIA 45x9 micr., 4-spored. TASTE and ODOR slight or some- 

 what disagreeable. 



Gregarious. On lawns, roadsides, or in frondose woods among 

 grass, etc. July-Sei>tember. Southern Michigan. Not infrequent 

 during a few seasons. 



This Russula is closely allied to the preceding section. Its de- 

 velopment has been carefully studied. When the caps are 4 mm., 

 or less broad the margin is definitely subinrolled. The texture of 

 the trama is then very firm and tough and the entire surface of 

 both cap and stem is covered, as seen under the microscope, by a 

 differentiated thin layer composed of short, dense, erect yellow 

 hairs or hyphae. These hyphae are continuous at first with the 

 trama but become separated in masses as the pileus and stem en- 

 large, adhering at length to the surface of the mature pileus and 

 stem as delicate, appressed, pulverulent-flocculose, sulphur-yellow 

 granules. The hymenium contains very numerous cystidia with a 

 dark-brown, granular content, which project into the subhymenium 

 and often connect with similarly colored hyphae which intermingle 

 with the gill-trama. ( Lactif eres. ) The young cystidia project above 

 the basidia but later are even with them. These brownish cystidia 

 give a brown-dotted appearance to the sides of the gills as seen 

 under low power of the microscope. 



Microchemical tests: G. (Plesh and" gills become rapidly light 

 blue, then dark blue.) S V. (Gills first turn reddish then slowly 

 blue; flesh scarcely affected.) F S. (Cystidia colored brown.) 



This species is easily confused in the old, discolored stage with 

 R. pectinatoides and R. foetentula, since both have a livid yellowish- 

 brown cap at times when mature, well marked tuberculate stria- 

 tions, and are about the same size. They lack, however, the peculiar 

 yellow granules of R. pulverulenta. (For further remarks see Mich. 

 Acad. Rep. 11, p. 77, 1909.) 



