KEY TO THE MORE IMPORTANT GENERA OF FAMILY THELEPHORACEAE ' 511 



ture may have arisen finally the holobasidium of Corticium. From the 

 latter as a starting point the greater complication of the hymenium lead- 

 ing to increased spore-bearing surface brings us to such famihes as Clava- 

 riaceae, Hydnaceae, and Polyporaceae. Within the latter there is a tend- 

 ency toward radially elongated pores or even lamellae. From some of the 

 fleshy Polypori with central stems may have arisen forms like the Bole- 

 taceae. Some of the latter have pores that are semilamellate. So there is a 

 possibility of the origin of the Agaricaceae from either of these families. 

 On the other hand there is an undeniable close relationship between a 

 number of the Agaricaceae and several genera of the Gasteromycetes. 

 Singer (1936) held that this indicates a descent of the former from the 

 latter. In this case the universal veil would represent a reduced peridium 

 and evolution within the Agaricaceae would have to be considered as 

 progressing from the angiocarpic through the pseudoangiocarpic to the 

 gymnocarpic forms. The chief objection to this theory is that it would 

 involve the transformation of the spore attachment from a symmetrical 

 one to the obliquely perched spore of the Agaricaceae. Inasmuch as the 

 theory further presupposes that the Gasteromycetes were evolved from 

 simple forms with obliquely attached spores this would involve the muta- 

 tion back again to the latter condition with an ancestral interphase of 

 symmetrical spore attachment. The further phylogenetic considerations 

 of these groups will be given more in detail in Chapter 17. 



Key to the Genera of Family Exobasidiaceae 



Mycelium intracellular; clusters of basidia, often among elongated paraphyses, 

 emerging from the stomata; basidia with two sterigmata. Kordyana 



Mycelium intercellular; basidia emerging from between the epidermal cells, usu- 

 ally four- to six-spored ; no paraphyses. Exohasidium 



Key to the More Important Genera of Family Thelephoraceae 



Hymenophore resupinate, floccose or continuous, of only one layer. 



Hymenophore floccose or felty or pellicular; basidia in scattered clusters, mostly 

 not forming a continuous hymenial layer. 

 Fructification tenuous with scanty subiculum, the hyphae distinct, loose; 

 basidia subglobose or short-claviform, with two to four stout, elongate, 

 more or less cornute or flexuous "epibasidia"; spores smooth, germi- 

 nating by repetition. See Ceratobasidium 



in Chapter 13. 

 Fructification mucedinoid, reticulate-pellicular, finely granulose; hyphae 

 short-celled, branching at right angles, often with formation of cruciform 

 cells; basidia in cymose, often candelabrum-like clusters, short cylindric 

 with four or six to eight sterigmata; spores mostly smooth but in a few 

 species spinulose; in some species spores germinating by repetition. 



Pellicularia 



(Botryobasidium) 

 Fructification felt-like or "hypochnoid," composed of loosely interwoven 

 hyphae; basidia in scattered clusters or sometimes in a compact, smooth 



