THELEPHORACEAE 473 



the Boletaceae and Fistulinaceae were united with the Polyporaceae. 

 Maire (1937) and Singer (1936) removed the Cantharellaceae from the 

 Agaricales to the Polyporales, but Heim (1934) retains this family in the 

 Agaricales. He recognizes two more orders intermediate between the Poly- 

 porales and Agaricales: the Boletales and the Aster osporales (including 

 the Russulaceae). 



Family Thelephoraceae. Hymenial surface smooth or at most only 

 slightly warty or folded. Spore fruits membranous, leathery, or in two or 

 more genera fleshy; closely appressed to the substratum or forming a 

 shelf or funnel or simple or divided pileus with hymenium on one surface 

 only. Twenty or more genera are recognized and probably about 1000 

 species. The most complete study of the North American species of this 

 family is that by E. A. Burt (1914-1926). Rogers and Jackson (1943) 

 have made a thorough nomenclatorial study of many of the resupinate 

 species of this family. 



The genus Corticium forms a thin spore fruit growing closely appressed 

 to the substratum and not distinguishable into several layers. The hymen- 

 ium arises directly from the mycelium and consists of a layer of closely 

 packed basidia. The margin of the spore fruits may be definite or indefi- 

 nite. When dry the hymenium is often cracked. There are no true cystidia 

 among the basidia but gloeocystidia may be present in some species. 

 Most of the species of the genus are saprophytic on wood or bark, a few 

 are destructive to wood. 



Miss Nobles (1937) demonstrated, by mating monocaryon cultures 

 of Corticium incrustansvon Hohn. &Litsch., that this species falls into two 

 sexual phases, i.e., is of the bipolar type of sexuality. Aerial hyphae of 

 monocaryon mycelium give rise to allantoid hyahne uninucleate conidia, 

 often many to a hyphal cell, which upon germination produce again the 

 monocaryon phase. The dicaryon aerial hyphae, which have a clamp 

 connection at every septum, produce a single binucleate conidium on each 

 hyphal cell, leaving two nuclei behind in that cell. These conidia upon 

 germination give rise immediately to dicaryon hyphae. 



The old genus Corticium has been divided into several genera, the dis- 

 tinctions being based chiefly upon the structure of the basidia and the 

 nature of the hymenium whether loose or compact. One of these genera, 

 Ceratohasidium, with two to six sterigmata so long and so much thickened 

 as to be called "epibasidia" shows close relationship to the Tulasneflaceae 

 and has been considered in the discussion of that family in the preceding 

 chapter. It represents about a halfway step between the Thelephoraceae 

 in the Eubasidiae and the Tulasneflaceae and Dacrymycetaceae in the 

 Heterobasidiae. Another genus, Pellicularia {Botryohasidium) has been 

 segregated by Rogers (1943) for those fungi formerly included in Corticium 

 which have a thin film of short, broad-celled mycelium on the substratum 



