AMERICAN WOOD-PRESERVERS' ASSOCIATION 17 



PENIOPHORA GIGANTEA 

 (Plate I, Fig. 3; Plate IV, Figs. 1-3) 



This fungus is usually most evident as a fluffy whitish mycelium 

 on the surface of the wood. On the ends of ties it forms radiating 

 streaks or ridges which consist of the mycelium intermixed with 

 exuding resin. The fungus is very often associated with blue stain. 

 When fruiting-bodies are formed they consist of smooth, flat, waxy 

 to subcartilaginous patches which are watery-white to creamy or 

 smoky gray in appearance. The margin is whitish and usually more 

 or less fluffy. As the plant dries it forms a brittle surface layer which 

 easily separates from the wood. 



While the fungus is distributed over a large part of the United 

 States, it occurs in greatest abundance in the southern half east of 

 the Rockies. In the north it is introduced principally on infected pine. 

 Ties are usually abundantly infected before reaching destination. For- 

 tunately the fungus does not produce any appreciable rot in the sap- 

 wood which it attacks, although the mycelium penetrates to a con- 

 siderable extent. Hence the inspector need not discriminate against it. 



HYPOCREA CITRINA 



(Plate II, Fig. 4; Plate VI. Figs. 3 and 4) 



This is one of the fungi which grow flat on the surface of the 

 wood. It closely resembles a spot of yellow paint and forms a crust 

 about & inch thick. The spores are borne in cavities just beneath the 

 surface of the fruit-body. It was noted several times, particularly on 

 beech. The wood beneath the fruit-bodies is markedly bleached, but 

 the tissues are not seriously disintegrated. In its action on the wood 

 it behaves a good deal like Schizophyllum commune and should thus 

 be classed with the slow-acting wood destroyers. 



HYPOXYLON COHAERENS 

 (Plate II, Fig. 1; Plate V, Figs. 5 and 7) 



The fruiting-bodies of this fungus consist of more or less globose 

 buttons, usually not exceeding T& inch in diameter. In the young stages 

 these are no larger than a pin head and are often covered with a clay- 

 colored "bloom." When mature they are black. 



This fungus has a rather wide distribution in the United States, but 

 has never been reported as serious outside the central hardwood region, 

 where it is limited to beech. The sapwood is first attacked, but finally 

 the heartwood is invaded. The configuration of the rot is peculiar, as 

 the fungus attacks the wood in small, irregular "islands," usually 

 radially elongate, which are bleached out and bounded by narrow brown 

 lines representing the sound wood. This gives an intricate tracery of 

 brown lines on a lighter background. In more advanced stages of the 

 rot the brown lines may disappear, giving a more or less uniform 

 bleached appearance to the wood. The rot is a serious one and should 

 be culled, as the infected areas show a marked softening and dis- 

 integration of the fiber. 



