PLEUROTUS OSTREATUS 477 



In the morning, one of us makes a strange confession : " I 

 dreamed I was in a gloomy forest and stood watching dense vohmies 

 of spore-smoke being given out by the metaboHc fires of a huge 

 Toadstool ; but, just as the fire brigade was coming, I awoke." 



At noon we again seek our Oyster Fungus. The temperature 

 is even higher than last night, the air very still, and the light fairly 

 good. Surely as many spores must be coming away from the gills 

 per minute as were coming during our nocturnal visit. Yet we see 

 none of them. The reason for our failure is that, although the spores 

 are illuminated by the light of day, we lack the deep blackness of 

 the night for our background. 



Pleurotus ostreatus. — Pleurotus ostreatus, the Oyster Fungus, is 

 lignicolous and forms its fruit-bodies in imbricating clusters on dead 

 or dying trunks and branches of trees. In the United States it has 

 been observed on Oak, Elm, Maple (Figs. 197 and 198), and Bass- 

 wood (Tilia).i In England I have often seen it on Beech (Vol. I, 

 Figs. 2 and 3, pp. 22 and 23), Poplar, and Holly, while, according to 

 Berkeley, 2 it is especially common on Laburnum. In England it 

 is distinctly a plant of the late autumn, for it is often at its best in 

 November and, if the weather is mild, may be seen flourishing even 

 hi December. Learn, ^ writing from Ithaca in the State of New York, 

 remarks that P. ostreatus is found from August to early December. 

 In England, the pileus of the variety with which I am best acquainted 

 is beautifully blue * during the first few days of its development ; 

 but, as the pileus increases in size and becomes older, this blue 

 colour gradually fades away and is replaced by yellowish-brown. 

 The diameter of well-developed pilei varies from 8 to 20 cm. (3-8 

 inches). At first the margin of the pileus is incurved (Fig. 199, 

 p. 483). The pileus extends itself by long-continued peripheral 

 growth, so that the oldest parts of the gills are by the stipe and 

 the youngest at the pileus-margin. If the weather is favourable, 

 a single fruit-body may persist in good condition and shed spores 



^ C. D. Learn, " Studies on Pleurotus ostreatus and Pleurotus tdmarius," Annales 

 Mycologici, vol. x, 1912, p. 542, also Plate XVI. 



2 M. J. Berkeley, Outlines of British Fungology, London, 1860. p. 136. 



^ C. D. Learn, loc. cit. 



* This blue has been compared to that seen on the neck of a dove (Columba). 



