1916] Yates: Histology of Calif or nian Bolctaceae 241 



above under Form C. In these plants, the tufts are. however, not 

 so widely separated from each othci- at the base as deseribed above 

 in the ease of Form C. The tufted surface layer is about 200/x in 

 thickness. The tufts are formed by hyphae arranged in a way very 

 similar td lluit of the tufts deseribed above, although the hyphae do 

 not branch so frequently. This difference in .structure is perhaps due 

 to the fact that the specimens referred to Form D are not so old as 

 are the plants described under Form C. The hyphae are brown in 

 color, 8 to lOfjL in diameter and from 20 to 30/x between the septa 

 (pi. 28. fig. 20). 



The structure of the hymenium is similar in every respect to the 

 hymenium of Form B previously described. 



The surface of the stipe is covered with a rind 12 to 15/x in 

 thickness, made up of interwoven brownish-colored hyphae 4/x in 

 diameter. Scattered over the surface we find tufts similar in everv 

 respect to those described on the vstipe in Form B (pi. 24, fig. 26). The 

 hyphae immediately below the surface rind lie very closely together 

 and are but little interwoven. They occupy a position parallel to 

 each other and to the long axis of the stipe. Toward the center of 

 the stipe the hyphae become larger (Sfx) in diameter and more closely 

 interwoven. The hyphae of the context are nearly hyaline, as is 

 usual in all these forms. 



Ceriomyces communis, Form E 



Plate 21, figure 3 



Some half-dozen plants collected in chaparral made up of maii- 

 zanita {ArctostapJnjlos canescens), coast live oak {Quercus agrifolia), 

 madrone (Arhittus Menziesii), Ceanothus thyrsiflorus, and hazel {Cory 

 lus rostrata var. califoniica) near Mill Valley, INIarin County, showed 

 certain rather important histological and morphological variations. 

 These plants are deposited in the Herbarium of tlie University of 

 California under No. 241. 



The pileus in these plants is 5 to 6 em. in (li.imctei-. thin (1 cm.), 

 nearly plane. The surface of tlie pileus is light hrowu in color and 

 tomentose. The context is light yellow or reddish hcneath the cuticle 

 ;ui(| (Iocs not cli;niL;-c to blue when wounded. The tubes are 4 to 

 5 mm. long, yellow changing to l)lue when bruised. The mouth of the 

 tubes are large, angular. The stipe is about 5 cm. long and 1.0 em. 

 in diameter, even, not enlarged below nor attenuate at the base, surface 



