H>4 STUDIES OF AMERICAN FUNGI. 



sinuate, white or nearly so. The spores are globose, 5-8 yu in diam- 

 eter. The stem is firm, eccentric, usually curved because of its lat- 

 eral attachment on the side of the tree, and the horizontal position 

 of the pileus. 



The elm pleurotus has been long known as an edible fungus, and 

 is regarded as an excellent one for food on account of its flavor and 

 because of its large size. It occurs abundantly during the late 

 autumn, and at this season of the year is usually well protected from 

 the attacks of insects. It occurs in the woods, or fields, more fre- 

 quently on dead trees. On shade trees which have been severely 

 pruned, and are nearly or quite dead, it sometimes appears at the 

 wounds, where limbs have been removed, in great abundance. In the 

 plants shown in Fig. 105 the stems are strongly curved because the 

 weight of the cap bore the plant downward. Sometimes when the 

 plant is growing directly on the upper side of a branch or log, the 

 stem may be central. 



Pleurotus ostreatus Jacq. Edible. This plant is known as the oyster 

 agaric, because the form of the plant sometimes suggests the outline 

 of an oyster shell, as is seen in Fig. 107. It grows on dead trunks 

 and branches, usually in crowded clusters, the caps often overlapping 

 or imbricated. It is large, measuring 8-20 cm. or more broad. 



The pileus is elongated and attached at one side by being sessile, 

 or it is narrowed into a very short stem. It is broadest at the outer 

 extremity, where it becomes quite thin toward the margin. It is 

 more or less curved in outline as seen from the side, being depressed 

 usually on the upper side near the point of attachment, and toward 

 the margin convex and the margin incurved. The color is white, 

 light gray, buff or dark gray, often becoming yellowish on drying. 

 The gills are white, broad, not much crowded, and run down on the 

 stem in long elevated lines resembling veins, which anastomose 

 often in a recticulate fashion. The spores are white, oblong, 7-10 /< 

 long. The stem when present is very short, and often hairy at the 

 base. 



The oyster agaric has long been known as an edible mushroom, 

 but it is not ranked among the best, because, like most Pleuroti, it is 

 rather tough, especially in age. It is well to select young plants. 

 Figure 107 is from plants (No. 2097, C. U. herbarium) collected at 

 Ithaca, N. Y. 



Pleurotus sapidus Kalchb. Edible. This plant usually grows in large 

 clusters from dead trunks or branches or from dead portions of living 

 trees. It grows on a number of different kinds of trees. The stems are 

 often joined at the base, but sometimes the plants are scattered over a 



