502 BRITISH FUNGI 



TUBERE^ 



Key to the Genera 



A. Gleba without veins, but having one or more cavities. 

 * Asci cylindrical. 



Spores warted, subglobose. Genea. 



** Asci broadly oblong or subglobose. 



Spores elongated, smooth. Balsamia. 



Spores globose, surface netted. Hydnobolites. 



Spores globose, warted. Hydnotrya. 



B. Gleba ivith permanent veins {dissepiments) , solid or lacunose. 

 Spores globose, smooth ; asci cylindrical. Stephensia. 

 Spores globose, warted ; asci elliptic-oblong. Pachyphlceus. 

 Spores elliptical or globose, netted, warted or spiny ; asci sub- 

 globose. Tuber. 



Spores globose with elongated, blunt \\'arts ; asci elliptic-oblong. 



Chceromyccs. 



Ascophore with a distinct obconic base ; spores globose, warted ; 



asci subglobose. Terfezia. 



Spores globose, hyaline, with long, very slender, spreading spines. 



Amylocarpus. 



Genea 



Ascophore fleshy, warted, with a perforation in the wall at the 

 apex, and a tuft of mycelium at its base ; gleba broken up into 

 cavities opening into the apical perforation ; asci cylindrical, 

 8-spored ; spores subglobose, colourless. 



G. verrucosa. — Ascophore irregularly lobed or grooN-ed, black, 

 minutely warted, apical opening often large, up to J in. across ; 

 asci narrowly elliptical, 8-spored ; spores globose or broadly ellip- 

 tical, colourless, warted, 25x20 /x, or 25x30 /*. 



Smell strong, unpleasant. 



Clay soil under oaks, chestnuts, etc. 



G. klotzschii. — Ascophore irregular in form, black, warted, 

 attached by black fibrils ; mycelium abundant, white, floccose, 

 about I in. diam. ; asci cylindrical, 8-spored ; spores subglobose, 

 colourless, rather coarsely warted, 25-30 i>. diam. 



Growing nearly on the surface of the soil in small groups, and 

 covered by a dense patch of white mycelium running over the sur- 

 face. Smell foetid. 



G. hispidula. — Ascophore subglobose, densely covered ^\■ith long, 

 bright brown hairs, apical opening almost hidden, up to | in. diam. ; 

 asci cylindrical, 8-spored ; spores globose or broadly elliptical, 

 25-30x20-25 /A, or 20-26 /J- diam. 



The internal cavity is often almost simple. Smell faint. 



Underground under cliestnut trees. 



