MICHIGAN ACADEMY OF SCIENCE. 79 



PiLEUS 5-10 cm. broad, fleshy, soon fragile, convex to piano-depressed, 

 rosy to hlood-red, sometimes faded to white, peUicle separable, margin strongly 

 tubercular-striate or even sulcate, viscid and shining. Flesh white, red under 

 the cuticle. Gills pure white, subdistant or close, distinct, rather broad, 

 ecjiial, broadest toward front, narrowly adnexed or free, interspaces venose. 

 Stem 4-7 cm. long, 1-2 cm. thick, white or tinged red, subeqiial, spongy-stuffed, 

 even. Spores white in mass, globose, echinulate, 7.5-10 micr. Taste 

 very acrid. Odor none. 



Scattered or gregarious. On the ground or on debris of very rotten logs 

 in woods. Thruout the state. July to October. Common. 



The myceUum has been found to be attached to oak tree roots where it 

 forms mycorrhiza. The very acrid taste gives it a bad reputation and it is 

 avoided by mushroom-eaters. Some think it is harmless when thoroughly 

 cooked, there are variations of habitat. It grows cjuite constantly on the 

 crushed remains of wood or logs, where its white strings of mycelium are easily 

 seen; here the gills are close. One form has been found growing in troops; 

 such were found in a tamarack swamp in late October, growing on thick beds 

 of sphagnum. They had developed somewhat differently as was to be ex- 

 pected. The stems were white, long and stout, narrower above and obsoletely 

 wrinkled. The gills were subdistant. The taste was sharp but not as ex- 

 cruciating as that of the type. The cUsk of the pileus is glabrous and very 

 viscid. It is a beautiful plant, apparently appearing late, it might be referred 

 to as var. gregaria. 



34. RUSSULA RUGULOSA Pk. 



(The rugulose Russula.) 



Illustrations: N. Y. State Mus. Rep. 54, 1901. PL 72, p. 179, fig. 12-18. 



PiLEUS 5-10 cm. or more broad, thin, fragile, convex then piano-depressed, 

 dark rose-red, color sometimes thin, surface almost entirely rugidose. the 

 rugae radiating somewhat, rather viscid, pellicle separable, margin at length 

 distinctly tubercular-striate. Flesh thin, white, red under pellicle. Gills 

 shining white, rather close, narrowly adnate, not very broad, broadest in front, 

 few forked, equal, interspaces venose. Stem white, subeciual, unchanged, 

 glabrous, spongy-stuffed. 6-7 cm. long, 1-2 cm. thick. Spores ivhite in mass, 

 globose, echinulate, 8-9 micr. Taste tardily but very acrid. 



In troops. Hemlock and mixed woods on the ground. August and Septem- 

 ber. Northern Michigan. 



Differs from R. emetica in its acrid taste developing slowly, in the uneven 

 and rather dull pileus and in the habit of appearing in troops on the ground. 

 It was formerly referred to R. emetica 'a,nd is close to it. 



35. Russula fragilis (Pers.) Fr. 



(The fragile Russula.) 



Illustrations: Hard's Mushrooms, 1908. P. 192, fig. 172. 



Pileus 2.5-5 cm. broad, very thin and fragile, convex then piano-depressed 

 with a thin viscid pellicle; tubercular-striate on the thin margin, glabrous, 

 rather uniform rosy or pcde red, sometimes faded or bleached to white. Flesh 

 ivhite under the pellicle, thin. Gills white, thin, close, crowded, adnexed, 

 ventricose, moderately broad. Stem 2-3.5 cm. long, .5-1 cm. thick, white, 

 spongy then hollow, equal, fragile. Spores white in mass, subglobose, 8-9 

 micr. Taste i^romptly and very acrid. Odor none. 



