MICHIGAN ACADEMY OF SCIENCE. 81 



38. RUSSULA TEN'UICEPS SP. NOV. 



(The thin-capped Russula.) 



PiLEUs 7-12 cm. broad, thin, fragile, convex to expanded, the somewhat 

 viscid pelhcle easily separable, margin at first connivcnt striate, deep rosy-red 

 or blood-red, sometimes white spotted or tinged with orange blotches, some- 

 times uniform red with or without minute rugae. Flesh white, red beneath 

 the cuticle, very fragile at maturity. Gills white, then yellow-ochraceous, 

 crowded, narrow, fragile, narrowly adnate to free, few forked, interspaces 

 venose, equal, Stem fragile, white or rosy-tinged, spongy-stuffed, subequal 

 or ventricose, obscurely rivulose, white wdthin and unchanged, 5-9 cm. 

 long, 2-2.5 cm. thick. Spores yellow-ochraceous , subglobose, C-S micr. echi- 

 nulate. Taste acrid, sometimes tardily but very acrid. Odor not marked. 



Gregarious. Mixed woods at Marcjuette, in oak and maple woods at Ann 

 Arbor. July and August. Rather freciuent. 



As in R. veternosa, it is proba]:)le that several forms are represented here. 

 The red Russulas are very troublesome, and we seem to have a considerable 

 number of forms with acrid taste and yellowish to deep ochraceous gills, 

 which can not be easily kept separate. All efforts to refer them to old species 

 like R. sardonia, R rugulosa, R. rosacea, etc. failed repeatedly; the fragile flesh, 

 and ochraceous almost alutaceous gills are too distinctive. The maturing of 

 the spores is sometimes' slow, and care must l)e taken to get a good spore 

 print in these red species. All the collections which I have referred here 

 showed red on some or all of the stems of each collection. Their edibility 

 was not tried. 



39. Russula aurantialutea sp. nov. 



(The acrid yellow Russula.) 



Pileus 5-10 cm. broad, thin, fragile, convex then piano-depressed, yellow 

 (citron to luteus), or with orange shades intermingled especially on the margin, 

 slightly tubercular-striate, pellicle viscid, shining and somewhat separable 

 for some distance. Flesh white, thin toward the margin, unchanged with 

 age. Gills pale yellow, close, or subdistant at the outer extremity, ecpal or 

 a few shorter, narrowly adnate, seceding with age, broadest toward front,' 

 often forked at the base, rarely elsewhere, interspaces venose, Stem 4-S 

 cm. long, 1.5-2 cm. thick, white, flesh concolor and unchanged, subeciual, 

 glabrous, even, spongy-stuffed. Spores ochraceous-yellow, subglobose, 8-9 

 micr. Taste acrid in all its parts, often very acrid. Odor not noticeable. 



Solitary or scattered. On debris or forest mould in hemlock or mixed 

 woods of northern Michigan, in deciduous woods in the southern part of the 

 state. July, August and September. Earlier in southern Michigan. In- 

 frequent. 



R. ochraleuca Fr. differs in having white to pallid gills and spores, and 

 cinerescent stem; R. granulosa Cke. has white gills and spores and granular 

 cap and stem. R. fellea Fr. has flesh ochraceous or straw-yellow, and the 

 more firm pileus either straw or gilvous, and its gills exude watery drops; 

 R. claroflava Grove has a cinerescent stem, gills white then lemon yellow tinged 

 ochre; R. ochracea Fr. has a mild taste, and the flesh of cap, gills and stem 

 is ochraceous; R. simillima Pk. has white spores and pale ochraceous pileus 

 and stem; and R. decolorans Fr. has cinerescent flesh and is stouter. 



Our species could be made an ecological variety of almost any of the above 

 species, depending on the guess of the author who so interpreted it. The 



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