10-2 



STUDIES OF AMERICAN FUNGI. 



C. U. herbarium) collected in woods near Ithaca, N. 

 autumn of 1899. 



PLEUROTUS Fr. 



Y., in the 



The genus Pleurotus is usually recognized without difficulty among 

 the fleshy, white-spored agarics, because of the eccentric (not quite 

 in the center of the pileus) or lateral stem, or by the pileus being 

 attached at one side in a more or less shelving position, or in some 

 species where the upper side of the pileus lies directly against the 

 wood on which the plant is growing, and is then said to be resupinate. 



The gills are 

 either decurrent 

 (extending 

 downward ) on 

 the stem, or in 

 some species 

 they are rounded 

 or notched at the 

 junction with the 

 stem. There is 

 no annulus, 

 though some- 

 times a veil, and 

 the genus re- 

 sembles both 

 Tricholoma and 

 Clitocybe, except 

 for the position 

 of the stem on 

 the pileus. In 

 Tricholoma and Clitocybe the stem is usually attached at the center, 

 and the majority of the species grow on the ground, while the species 

 of Pleurotus are especially characterized by growing on wood. Some 

 species, at least, appear to grow from the ground, as in Pleurotus 

 petaloides, which is sometimes found growing on buried roots or 

 portions of decayed stumps which no longer show above ground. 

 On the other hand species of Clitocybe, as in C. Candida (Fig. 91), 

 often have an eccentric stem. This presents to us one of the many 

 difficulties which students, especially beginners, of this group of 

 fungi meet, and also suggests how unsatisfactory any arrangement 

 of genera as yet proposed is. 



Pleurotus ulmarius Bull. Edible The elm pleurotus is so called 



FiGURK 105. Pleurotus ulmarius. Cap white, or with shades of yellow 

 or brown near the center (natural size). Copyright. 



