[Vol. 2 



700 ANNALS OF THE MISSOURI BOTANICAL GARDEN 



larger hyphae might belong to some other fungus living 

 within the tissues of this species. This supposition is ren- 

 dered improbable, however, by the fact that they are in- 

 variably present in all collections, and that while other fungi 

 frequently attack all of these white species, their hyphae are 

 invariably much smaller than those of the fungi attacked. 



The evidence seems very clear, however, that these two 

 species should be considered as distinct. When once differ- 

 entiated they can usually be separated on the basis of their 

 general habit, without recourse to the character of the 

 branched or unbranched hyphae in the context, though that 

 character can always be relied upon in establishing beyond a 

 doubt the identity of the species. In other characters the two 

 species are very similar. Both are glabrous or practically so ; 

 are covered with a thin grayish or yellowish pellicle that be- 

 comes more evident when the plants are dried; have a sweet 

 acid odor when fresh, a soft and friable context when dry; 

 and the spores are the same, being cylindric, often slightly 

 curved, and measuring 3-4x0.7-1.5 ft. There are no cystidia. 



There is considerable doubt in the writer's mind as to 

 whether the true P. lacteus occurs in this country. There is 

 a collection in the herbarium of the Missouri Botanical Garden 

 and another in the writer 's herbarium that should perhaps be 

 referred to that species, but the hymenium has been dis- 

 organized by the growth upon it of another fungus, so that 

 no spores are present. If future collections should show that 

 the spores are similar to those of P. chioneus, the plants 

 should in all probability be referred to P. lacteus. The pileus 

 is somewhat strigose or fibrillose-pubescent, though the 



mouths of the tubes are not labyrinthiform. The pileus is too 

 pubescent for either P. chioneus or P. albellus to which latter 

 species the plants were once referred by Lloyd. It is possible 

 that they represent P. lacteus as more recently defined by 

 Lloyd. 1 I have seen no specimens so referred by him and his 

 description of the plant as "a common white species'' and 

 again as "a frequent plant" throws some doubt on my 

 opinion, for the plant is a rare one. 



1 Letter No. 49, p. 14. 



