248 University of California Puhlications in Botany [Vol. 6 



yellow, smooth, oblong-ellipsoid, 9-11 by 3-4^; stipe enlarged above, usually 

 tapering below, but sometimes bulbous, very variable in size, 5-9 cm. long, 

 0.5-1 cm. thick, colored and clothed like the pileus, distinctly and beautifully 

 reticulate, sometimes entirely to the base. 



While not a Californian plant, the description of C auriflammeiis 

 is placed here to increase the amount of material for comparison. 



Histology 



The surface of the pileus is but very slightly differentiated in the 

 single specimen examined. There is, however, a layer of densely 

 compacted hyphae some 20/a in thickness. This layer is made up of 

 brownish hyphae 3 to 5/* in diameter which are frequently branched 

 and densely interwoven. The context of the pileus is formed of 

 interwoven hyaline hyphae 6 to 10/a in diameter. 



The hymenium resembles that of Cerioniyces communis, Form B, 

 in every detail. 



The rind of the stipe presents a very characteristic appearance in 

 this plant. The surface is covered with a rind some 50 to 70/i, in 

 thickness. This rind is formed by the swollen tips of hyphae which 

 curve outward until they lie in a position perpendicular to the surface. 

 The individual hyphal tips vary greatly in their shape ; usually, 

 however, they are club-shaped, oval, or elongated. The are 8 to 12ju, 

 in diameter and contain a granular substance which is probably oil 

 from its general appearance. The hyphae of the context of the stipe 

 increase in diameter as the center of the stipe is approached. Those 

 immediately beneath the rind are usually about 4 to Gfx. in diameter, 

 while at the center the hyphae may attain a diameter of 20 to 25ix. 

 All the hyphae of the context are hyaline and lie in a position nearly 

 parallel to each other and to the long axis of the stipe (pi. 24, fig. 25). 



SUILLELLUS IMurrill 



Suillellus is a genus instituted by ]Murrill {Mycologia, Vol. 1, No. 1, 

 January 1909) to include plants previously referred to the section 

 ^^ LuridV^ of the genus Boletus of Fries and later Avriters. Unlike 

 other genera instituted or adopted by Murrill, Suillellus is not charac- 

 terized by any morphological character which can be determined in 

 dried material. It differs from Cerioniyces only in one particular 

 and that is that the mouths of the tubes are red, and this red color is 

 not due to any permanent structure but simply to a red pigment which 



