THE AGARICACEAE OF MICHIGAN 



tested, and all, except perhaps the edible P. cervinus, are too small 

 t«i consider from a food-value standpoint. 



The species can for the most part only be identified with the 

 aid of a microscope, since the character of the cystidia must be 

 known before certainty can prevail. Hence the following key is 

 based on the only certain method which can be followed in this 

 genus. Of the species not yet found in the State, P. stercorwrius 

 Pk. -lows on manure heaps, and its spores are exceptionally large, 

 measuring L2-15 micr. long; P. sterilomarginatus Pk. has angular 

 spores. 1 1 is possible that P.leurotus subpalmatus Fr. which as it 

 occurs with us is well illustrated by Cooke under Pluteus phlebo- 

 phorus, Plate 122, P., has been reported as a Pluteus; its adnate 

 gills, however, should prevent confusion: 



Pries divided the genus into three sections, given below. 



Key to the Species 



(A) Pileus white or whitish. [See also (AA) and (AAA).] 



(a) Cystidia with 2-4 horns at apex; pileus subglabrous to fibrillose 



or rimose, 5-15 cm. broad. 574. P. cervinus Fr. var. albus Pk. 

 (aa) Apex of cystidia without horns; pileus villose-tomentose, 2-7 cm. 



broad. 578. P. tomentosulus Pk. 

 (aaa) Cystidia rare, not pronged; pileus glabrous, 2-3 cm. broad. 579. 

 P. roscocandirlus Atk. 

 (AA) Pileus yellow, orange or red. 

 (a) Pileus orange to vermillion; spores short-oblong. 582. P. calocens 



Atk. 

 (aa) Pileus yellow, sometimes smoky tinged, 

 (b) Pileus rugose-reticulate on disk, 

 (c) Stem stuffed to hollow, yellow; pileus glabrous, umbonate. 



584. P. admirabilis Pk. 

 (cc) Stem solid, pinkish-white; pileus 4-5 cm. broad, smokv velvety 

 on disk. P. flavofuligineus Atk. 

 (bb) Pileus not rugose on disk, striate on margin; stem pellucid- 

 white. 585. P. leoninus Fr. 

 (AAA) Pileus brown, fuscous, umber, blackish, etc. 

 (a) Cystidia with 2-4 horns at apex; pileus not striate on margin; stem 

 fibrillose. 



(b) Gills with their edges smoky-brown. 575. P. umbrosus Fr. 

 (bb) Gills unicolorous. 



(c) Pileus usually rather large, 3-15 cm. broad; color dingv pale 



brown, but variable; common. 574. P. cervinus Fr 

 (cc) Pileus small to medium; pileus and base of stem tinged bluish 

 or with a distinct olivaceous tinge; cystidia longer than in 

 the preceding; rare. 576. P. salicinus Fr. 

 (aai ( ystulia without horns at apex. 



Hi) Pileus not truly striate on the margin 

 (c) Stem glabrous, pellucid, innately striatulate. 

 (d) Stem and gills white at first. 581. P. nanus Fr. 

 (dd) Stem and sometimes the gills, yellowish. 581. P. nanus 

 var. lutescens Fr. 



(C ?ii S ^T velvety t0 squamulose. brownish, etc 



' , • ° f T,f Uls ° f same color - ^stidia hyaline. 580. P. gran- 



ularis Pk. 



(dd) Edge of gills with yellowish cystidia. 580. P. granulans 

 Pk. var. umbroselhis Atk. 



