- , , THE AGARICACEAE OF MICHIGAN 



branaceous. (JILLS narrowly adnate, attenuate behind, sometimes 

 free, yellow, then sordid pale cinnamon, moist and somewhat dis- 

 solving. STEM 7-9 cm. long, 2-3 mm. thick, fragile, hollow, slight- 

 ly attenuated upwards, glabrous, naked at apex, yellow. SPORES 

 elliptical, smooth, 11-13x6-7 mier., rusty-ochraceous. 



Solitary or gregarious. In cultivated fields. Ann Arbor. May- 

 July. Infrequent. 



This is rather difficult of separation from B. vitellimis. It differs 

 apparently in its less plicate pileus and the naked, more yellow 

 stem; bu1 these characters are variable in this genus and inter- 

 mediate forms seem to be quite frequent. 



534. Boibitius vitellinus Fr. 



Syst. Myc, 1821. 



Illustrations: Cooke, 111., PL 923. 



(lillet, Champignons de France, Xo. 47. 

 Ricken, Blatterpilze, PL 23, Fig. 9. 



PILEUS 2-5 cm. broad, at first oval, obtuse and egg-yellow, at 

 length campanulate-expanded, cinereous toward margin, sulcate- 

 striate or plicate up to the egg-yellow obtuse umbo, viscid, glabrous, 

 margin at first straight. FLESH very thin. GILLS narrowly 

 adnate, close, subdistant at full expansion of pileus, narrow, soft, 

 ochraceous-clay-color and with white edge when young, rusty-ochra- 

 ceous in age, scarcely dissolving in wet weather, crisped in dry 

 weather. STEM 6-12 cm. long, 2-4 mm. thick, equal or slightly 

 tapering upward, slender, fragile, pruinose-scaly at apex or through- 

 out, white or slightly sulphur yellow-tinged, often pellucid-shining, 

 even or innately tihrillose. SPORES elliptical, smooth. 10-12.5 x 

 '''7.:. mier., rusty-ochraceous. Hymenium with large, ' inflated, 

 sterile cells intermingled with basidia and of the same length as 

 iln- basidia bu1 much broader. ODOR and TASTE none. 



<>n dun-, especially cow dung, in fields, woods, etc., where cows 

 ■"'• pastured. Ann Arbor, New Richmond, probably throughout 

 the State. May-July. Rather frequent. 



To be looked for in early .June. It is a rather variable plant, 

 changing in color as it develops, and again as it ages. Some speci- 

 mens have while stems, others have stems tinged with sulphur- 

 yellow. Tin- distinctive character is the egg-yellow umbo on the 

 '•'""•'- of the ]. ileus, and before expansion the whole pileus is 



