WHITE-SPORED AGARICS. 105 



portion of the branch or trunk. The cap is from 5-10 cm. broad. 

 The plants occur from June to November. 



The pileus is convex, the margin incurved when young, and more 

 or less depressed in age, smooth, broadened toward the margin and 

 tapering into the short stem, which is very short in some cases and 

 elongated in others. Often the caps are quite irregular and the mar- 

 gin wavy, especially when old. It is quite firm, but the margin splits 

 quite readily on being handled. The color varies greatly, white, 

 yellowish, gray, or brownish and lilac tints. The flesh is white. 

 The stems are usually attached to the pileus, at or near one edge. 

 The gills are white, broad, not at all crowded, and extend down on 

 the stem as in the oyster agaric. They are white or whitish, and as 

 in the other related species are sometimes cracked, due probably to 

 the tension brought to bear because of the expanding pileus. The 

 spores are tinged with lilac when seen in mass, as when caught on 

 paper. The color seems to be intensified after the spores have lain 

 on the paper for a day or two. 



It is very difficult to distinguish this species from the oyster 

 agaric. The color of the spores seems to be the only distinguishing 

 character, and this may not be constant. Peck suggests that it may 

 only be a variety of the oyster agaric. I have found the plant 

 growing from a dead spot on the base of a living oak tree. There 

 was for several years a drive near this tree, and the wheels of 

 vehicles cut into the roots of the tree on this side, and probably so 

 injured it as to kill a portion and give this fungus and another one 

 {Polystidus pergamenus) a start, and later they have slowly 

 encroached on the side of the tree. 



Figure 108 represents the plant (No. 3307, C. U. herbari^^ra) 

 from a dead maple trunk in a woods near Ithaca, collected during the 

 autumn of 1899. This plant compares favorably with the oyster 

 agaric as an edible one. Neither of these plants preserve as well as 

 the elm pleurotus. 



Pleurotus dryinus Pers. Edible. Pleurotus dryinus represents a sec- 

 tion of the genus in which the species are provided with a veil when 

 young, but which disappears as the pileus expands. This species 

 has been long known in Europe on trunks of oak, ash, willow, etc., 

 and occurs there from September to October. It was collected near 

 Ithaca, N. Y., in a beech woods along Six-mile creek, on October 

 24th, 1898, growing from a decayed knothole in the trunk of a living 

 hickory tree, and again in a few days from a decayed stump. The 

 pileus varies from 5-10 cm. broad, and the lateral or eccentric stem 

 is 2-12 cm. long by 1-2 cm. in thickness, the length of the stem 



