190 STUDIES OF AMERICAN FUNGI. 



never tried it. Figure 183 is from a plant (No. 1930, C. U. herba- 

 rium) collected in Cascadilla woods, Ithaca. 



Polyporus sulphureus ( Bull. ) Fr. Edible. {Boletus caudicinus 

 Schaeff. T. 131, 132: Polyporus caudicinus ^chxoeiex , Cohn^sKxy^X. 

 Flora, Schlesien, p. 471, 1899). The sulphur polyporus is so-called 

 because of the bright sulphur color of the entire plant. It is one of 

 the widely distributed species, and grows on dead oak, birch, and 

 other trunks, and is also often found growing from wounds or knot- 

 holes of living trees of the oak, apple, walnut, etc. The mycelium 

 enters at wounds where limbs are broken off, and grows for years in 

 the heart wood, disorganizing it and causing it to decay. In time the 

 mycelium has spread over a considerable area, from which nutriment 

 enough is supplied for the formation of the fruiting condition. The 

 caps then appear from an open wound when such an exit is present. 



The color of the plant is quite constant, but varies of course in 

 shades of yellow to some extent. In form, however, it varies greatly. 

 The caps are usually clustered and imbricated, that is, they overlap. 

 They may all arise separately from the wood, and yet be overlap- 

 ping, though oftener several of them are closely joined or united at 

 the base, so that the mass of caps arises from a common outgrowth 

 from the wood as shown in Fig. 184. The individual caps are flat- 

 tened, elongate, and more or less fan-shaped. When mature there 

 are radiating furrows and ridges which often increase the fan-like 

 appearance of the upper surface of the cap. Sometimes also there 

 are more or less marked concentric furrows. The caps may be con- 

 vex, or the margin may be more or less upturned so that the central 

 portion is depressed. When young the margin is thick and blunt 

 and of course lighter in color, but as the plant matures the edge is 

 usually thinner. 



In some forms of the plant the caps are so closely united as to 

 form a large rounded or tubercular mass, only the blunt tips of the 

 individual caps being free. This is well represented in Fig. 185, from 

 a photograph of a large specimen growing from a wound in a butter- 

 nut tree in Central New York. The plant was 30 cm. in diameter. 

 The plants represented in Plate 69 grew on an oak stump. The 

 tree was affected by the fungus while it was alive, and the heart 

 wood became so weakened that the tree broke, and later the fruit 

 form of the fungus appeared from the dead stump. 



The tubes are small, and the walls thin and delicate, and are 

 sometimes much torn, lacerated, and irregular. When the mycelium 

 has grown in the interior of a log for a number of years it tends to 

 grow in sheets along the line of the medullary rays of the wood or 



