3916] Yates: Histology of Californian Bolctaceae 235 



eastern United States all (liftVr in certain details from Califoi'iiian 

 plants referred to the same species, and as a consequence I find that 

 the Californian material, although referred by the ordinary characters 

 to the same species as the eastern material with which it is compared, 

 does differ suffieiently to compel tH)nsid('rati()n in so far as the discus- 

 sion of the histological details is concerned. 



Ceriomyces communis (Bull.) ^lurrill 



Ceriomyccs communis, at least so far as the general agreement 

 with the description of that species is concerned, is a rather common 

 plant in the San Francisco Bay region. It here occurs in open or 

 shady woods and always under or in the vicinity of some species of 

 Quercus, usually Quercus agri folia. The plants begin to appear in 

 October and continue coming up from time to time under favorable 

 conditions of moisture and temperature until February or perhaps 

 even later. In the study of the living plants as they occur in the Bay 

 region, four distinct forms or varieties were noted, differing from each 

 other not only in certain minor morphological characters, but also in 

 certain histological details of seeming importance and constancy. For 

 the above reasons there has been made a more detailed study of these 

 plants, perhaps, than of others of which material is either not so 

 abundant or where such marked variation has not been met with. 



Taking jMurrill's (1910) description as a basis, Ceriomyces com- 

 munis may be distinguished by its plane (not reticulate) stipe, the 

 tomentose or roughened surface of the pileus. and the large, angular 

 tubes which change to blue where wounded. The pileus is convex to 

 plane or depressed with age, varying in diameter from 4 to 8 cm. The 

 surface of the pileus is tomentose to cottony, with minute scales, or 

 often rimose-areolate and varies in color from reddish to purple or 

 becoming brown in older individuals. The context is usually from 1 

 to 2 cm. in thickness, varying in color from yellowish-white to flavous, 

 and usually changing to blue or greenish where wounded. The context 

 of the pileus is often red beneath the cuticle. The margin is entire. 

 The tubes are adnate, and slightly decurrent, convex in mass or oc- 

 casionally depressed with age. The yellow or yellowish-green tubes 

 change quickly to greenisli-l)lue when wounded. The large moutlis of 

 the angular and irregular tubes are 0.5 to 1.0 mm. in diameter. The 

 smooth, spindle-shaped spores are olivaceous when fresh, fading to a 

 pale brownish color. The spores measure 11 to 13 by 4 to 5/^. The 



