520 CLASS BASIDIOMYCETEAE 



Veil none; stipe not viscid; pileus sometimes sub-tomentose, not pulver- 

 ulent; cuticle often consisting of a trichodermium (i.e., a palisade of 

 parallel, vertical hyphae) ; stipe usually swollen below but sometimes 

 cylindrical, often reticulately marked but not provided with glan- 

 dulae; stipe not with furfuraceous or squamulose scabrosities; pores 

 small; tubes usually long. Boletus 



Veil none; stipe not viscid, slender and tapering upward, scabrous; 

 spores naviculate; pores very small; tubes long, depressed around 

 stipe. Leccinum 



Pores round; spore print rusty yellow; spores under microscope golden 

 yellow; veil absent; stipe entirely smooth, equal or ventricose; stipe 

 never reticulate. Xanthoconium 



Pores round; spore print flesh color or vinaceous; veil absent; tubes more 

 or less flesh-colored; stipe often reticulate. Tylopilus 



Tubes divergent from one another at maturity as the pileus spreads; only known 

 from Madagascar. Ixechinus 



Keys to the More Important Genera of Family Agaricaceae^ 



(Modified from Key by A. H. Smith, 1938) 



Trama of pileus and usually of the gills composed of nests of sphaerocysts sur- 

 rounded by connective tissue and with lactifers irregularly dis- 

 persed throughout. (By many recent students considered as 

 Family Russulaceae.) 

 Cut or broken parts of the fruiting body exuding a watery to milk-like or 



colored latex. Lactarius 



No latex present; fruiting body often very fragile. Ritssula 

 Trama of pileus not with sphaerocysts. 



Parasitic upon other agarics; flesh of cap breaking down into a mass of chlamy- 

 dospores. Asterophora 



(Nyctalis) 

 If parasitic on agarics, flesh not breaking down into chlamydospores. 

 Hymenium typically waxy; spores smooth. 



Spore print white. Hygrophorus 



(including Hygrocybe, Camarophtjllus, Lim.acium) 

 Spore print smoky gray to blackish. Goynphidius 

 Hymenium not waxy, or if appearing so, the spores echinulate. 



Fruiting body typically rather tough, if fleshy, or membranous and very 

 pliant; reviving when remoistened. 

 Gills with distinctly dentate to serrate edges. Lentinus 



(including Panus) 

 Gills with edges even, or merely slightly fimbriate. 



Stipe eccentric, lateral, or wanting (usually not reviving when re- 

 moistened) . Pleurotus 



* Used in the wider sense of the term. It should be noted that these keys of the 

 Agaricaceae are merely artificial keys by which to determine the genera and do not 

 represent a system of classification based upon phylogenetic considerations. Singer 

 (1936, 1949) has divided the gill fungi (Agaricaceae in the older sense) into many 

 families and split up many more of the genera; the bases of segregation being largely 

 the structure of the gills and type; of surface structure (cuticle, etc.) and the structure 

 of the spores, as well as the chemical character of the spore and hyphal walls. His 

 system is, so far as possible, based upon supposed true phylogenetic relationships. 



