314 University of California Puhlications in Botany [Vol. 6 



Tuber (Eutuber) gibbosum Hk. 



Plate 29, fig. 15 

 Proe. Cal. Acad. Sei., 3(1 ser., vol. 1, no. 8 (1899), p. 273. 



Ascocarp "cinnamon-brown," 1.5 cm. in diam., convolute, surface 

 minutely scabrous, gleba ochraceous ; veins barely distinguishable ; 

 outer cortical cells forming branched, knotted hairs parallel with sur- 

 face ; inner cortical tissue pseudoparenchymatous, deeply colored, 

 changing to colorless laterally extending hyphae of subcortex ; thick- 

 ness of peridium 200/x ; venae internae of long, compactly arranged 

 but unconnected hyphae ; venae externae of loose, spongy tissue com- 

 posed of branched, irregular hyphae, 4-5/x thick ; venae externae 

 opening in depressions of surface, depressions filled with parallel, 

 irregular, colored hairs of surface of ascocarp ; spores dark brown, 

 long-ellipsoid, pointed at ends, 28-38 by 36-52ju, (mostly 32 by 44/x) 

 alveolate, mostly 6 by 7 alveoli across diameters, sculpturing 4ju, thick. 



"Under oaks. Mill Valley, Marin Co., Calif., April." 



No. 162 Hk. Col. Type. 



Of this species only one specimen is found in the Harkness collec- 

 tion, and from this a small section has been removed. The plant is 

 infested with what appears to be an ascomycetous parasite which has 

 nearly destroyed the tissue of the gleba, making a study of this struc- 

 ture difficult. However, occasional unaffected portions are to be 

 found, and is possible from the material to describe all parts of the 

 ascocarp except the asci, which have almost entirely disappeared, only 

 occasional pieces of membrane remaining. The size and shape of the 

 asci, therefore, and the number of spores they contain cannot be de- 

 termined with accuracy. Through the venae internae, which in most 

 cases are found to have more or less completely disintegrated, run 

 long, coarse, branched hyphae, which apparently belong to the 

 parasite. 



This species seems to come nearest T. oligosporum as it is described 

 by Vittadini who established it. Like the Harkness specimen, T. oli- 

 gosporum is said to be lobed, with venae externae opening in depres- 

 sions filled with hyphae. The surface is illustrated as conspicuously 

 verrucose, however, the color of the ascocarp is described as reddish 

 black, that of the gleba and spores as sooty white, and the spore shape 

 is simply stated as oval. There are no measurements. A distinguish- 

 ing point used by Vittadini is the odor, which cannot be determined 

 ill the alcoholic material The character of the surface and the colors 

 cit(.'d do not agree with those of the Harkness material, as will be seen 



