230 University of California Puhlications in Botany [Vol. 6 



becomes the hymenium. At first this layer is quite smooth, then 

 slight elevations appear which are formed by the differential down- 

 ward growth of the hyphae. As the hyphae grow downward they 

 branch and curve outward on each side to form the hymenium. While 

 the hymenium is being differentiated, the ends of the hyphae from 

 below, which were cut off' by the formation of the annular furrow, 

 project upward to form a palisade layer. This palisade layer is car- 

 ried downward during the elongation of the stipe and forms the sur- 

 face rind of, at least, the upper portion of the stipe. From the above 

 description it is evident that at no time during the development of the 

 fruiting body, is there any evidence of a veil being present in this 

 species of Ceriomyces. 



Structure of the Stipe 



The stipe is usually, though not always, differentiated into an outer 

 or surface rind and a context. The context is made up either of hyphae 

 lying parallel to each other or, in other plants, the hyphae branch 

 more or less and are sometimes quite intricately interwoven. In either 

 ease, however, they always maintain a general position parallel to the 

 long axis of the stipe. Usually the hyphae become greater in diameter 

 and less closely interwoven as the center of the stipe is approached. 

 In some species the hyphae toward the center of the stipe are so 

 loosely interwoven that they break apart during growth. This results, 

 in extreme cases, in a stipe which is either hollow or fibrous. 



The surface of the stipe is usually differentiated to some degree at 

 least. In the forms in which the least differentiation is found, the 

 surface layer consists merely of very closely packed hyphae, lying 

 parallel to the long axis of the stipe and differing from the hyphae of 

 the context only slightly in size and in having a darker color. In all 

 the plants examined by the writer the hyphae of the context were 

 colorless, or at most slightly granular in appearance, while those of the 

 surface layer were some shade of yellow or brown. 



In many of our Calif ornian species of Boleti we find a distinct 

 rind covering the stipe. This rind is usually formed of branches 

 from the context curving outward until their tips stand in a position 

 perpendicular to the surface of the stipe. These branches may be 

 either larger or smaller in diameter than are the hyphae of the con- 

 text. The tips of the hyphae forming the rind are often more or less 

 swollen. In a few species reticulations are found on the stipe. These 

 reticulations are usually folds of the rind. 



