308 STUDIES OF AMERICAN FUNGI. 



Hymenium smooth (not as in B, though it may be con- ^ 



volute and irregular, or ribbed, or veined) 3 



2 Hymenium usually on the under side, in the form of radi- 

 ating plates, or strong folds. The genus Phlebia in the 

 HydnaceiE has the hymenium on smooth, somewhat 

 radiating veins which are interrupted and irregular. One 

 exotic genus has the hymenium on numerous irregular 

 obtuse lobes (Rhacophyllus) . Agaricaceas. . . 17 



Hymenium usually below (or on the outer surface when 

 the plant is spread over the substratum) , honey-combed, 

 porous, tubulose, or reticulate ; in one genus with short, 

 concentric plates Polyporaceae. . 171 



Hymenium usually below (or on the outer surface when 

 the plant is spread over the substratum), warted, tuber- 

 culate, or with stout, spinous processes ; or with inter- 

 rupted vein-like folds in resupinate forms Hydnaceaj. . . 195 



3 Plants somewhat corky or membranaceous, more or less 

 expanded ; hymenium on the under surface (upper sur- 

 face sterile), or on the outer or exposed surface when 

 the plant is spread over the substratum (margin may 

 then sometimes be free, but upper surface, i.e., that to- 

 ward the substratum sterile). (Minute slender spines are 

 sometimes intermingled with the elements of the hyme- 

 nium, and should not be mistaken for the stouter spi- 

 nous processes of the Hydnaceae) Thelephoraceae. 208 



Plants more or less fleshy, upright (never spread over the 

 surface of the substratum), simple or branched. Hyme- 

 nium covering both sides and the upper surface. , . . Clavariaceae. . 200 

 4 Basidia forked or longitudinally divided ; or if continuous 

 then globose, or bearing numerous spores; or if the 

 plant is leathery, membranous, or floccose, then basidia 

 as described. Hymenium covering the entire free sur- 

 face or confined to one portion ; smooth, gyrose, folded 

 or lobed ; or hymenium lamellate, porous, reticulate or 

 toothed forms which are gelatinous and provided with 

 continuous basidia may be sought here Tremellineae. . 204 



FAMILY AGARICACEJE. 



Pileus more or less expanded, convex, bell-shaped ; stipe central or nearly so ; 

 or the point of attachment lateral, when the stipe may be short or the pileus ses- 

 sile and shelving. Fruiting surface usually on the under side and exposed toward 

 the earth, lamellate, or prominently folded or veined. Lamellae or gills radiating 

 from the point of attachment of the pileus with the stipe or with the substratum 

 in the sessile forms; lamellze simple or branched, rarely anastomosing behind, 

 clothed externally on both surfaces with the basidia, each of which bears four 

 spores (rarely two), cystidia often present. 



Key to the North American Genera. 



