1916] Yates: Histology of California n Boletaccae 243 



it has never been found except this one time it is impossible to state 

 definitely that this was the normal time for it to appear. 



In studying the living' plants referred to Ccrionij/ccs crassus as 

 we find them grrowing in the San Francisco Bay region we find two 

 quite distinct forms, differing' not only in certain histological characters 

 but also in certain seemingly important morphological details. 



Taking: IMurill's description as a basis, Ceriomyces crassus may be 

 distinguished from other North American species of this genus by 

 its smooth or reticulate stem and the color of the tubes, which are 

 some shade of yellow or brown, usually becoming darker with age and 

 changing to greenish-ochraceous when wounded. The tubes are stuffed 

 when young. The plants are gregarious or eespitose. growing on the 

 ground or rarely solitary on much decayed wood. Ceriomyces crassus 

 is usually a large plant. The pileus is 6 to 20 cm. broad and 3 to 4 cm. 

 thick, while the stipe is 5 to 10 cm. long by 3 to 4 cm. in diameter. 

 The pileus is broadly convex with a dry (or viscid when moistened) 

 subopaque surface, ochraceous brown to reddish brown in color, and 

 glabrous or finely tomentose. The tlesh is firm, white or yellowish in 

 color or sometimes reddish beneath the cuticle. Tlie flesh does not 

 change in color when wounded. The taste is sweet and nutty. The 

 tubes are adnate, plane in mass or at length depressed. The angular 

 mouths are medium-sized with thin edges. The greenish yellow or 

 ochraceous-brown spindle-shaped spores are 13 to 15 by 5 to 6/x. 

 The solid stipe is subequal or enlarged below. The stipe is con- 

 colorous or paler, becoming blui.sh or discolored when wounded. Tlie 

 .surface of the stipe is either wholly or partially reticulate. The 

 context of the stipe is tough and fibrous, yellowisli within and often 

 tinged with red near the surface. 



Because of the variation in our Californian plants referred to 

 Ceriomyces crassu.'< by Dr. ]\luri*ill it has seemed necessary, in order 

 to discuss the rather pronounced morphological and histological differ- 

 ences, to designate our jtlants as Form A, Form B, etc. 



Ceriomyces crassus var. separans (Batt.) Peck 



Plate 22, figure 13 

 A single specimen of this variety from the eastern United States 

 was contributed by Dr. W. A. Murrill and is described here for pur- 

 poses of comparison. Since the specimen was dried nothing definite 

 can be said of the color characters. The only distinctive difference 

 noted between this plant and our Californian Form A is the shape 



