34 



BULLETIN 510, U. S. DEPARTMENT OF AGElCtJLTUKE. 



Of the fungi having a smooth under surface, two species are 

 common enemies of structural timber — StereuTn fasciatum Schw, 

 (PI. VIII, figs. 3 and 4) and 8. lohatum Knze. These fungi are 

 too much alike for the layman to attempt to distinguish between 

 them. They are very thin and flexible, the individual shelves often 

 growing one above the other. The general color is grayish to creamy. 

 Among the incrusting forms three deserve particular attention, 

 \iz, Merulius lachrymans (Wulf.) Fr., Coniophora puteana (Schum.) 

 Fr. ( = ^'. cevebella (Pers.) Schrot.), a.ndi Peniophor a gig ante a (Fr.) 

 Mass. The first two species are notoriously dangerous and have been 



found in a number of lum- 

 beryards extending from 

 Massachusetts to the Gulf 

 of Mexico. They are also 

 the most frequently re- 

 ported of all fungi occur- 

 ring in buildings, and also 

 the most destructive. 



M erulius lachrymans 

 (PL II, figs. 1, 2, and 6, 

 and PL IX, figs. 1 and 2) 

 is a soft, subgelatinous 

 fungus, forming a brown, 

 crumpled growth with a 

 white, fluffy margin over 

 the surface of timber. As 

 it develops it produces 

 dirty gray to brownish 

 minutely porous strands, 

 which serve for the con- 

 duction of water, thus en- 

 abling the fungus to 

 spread rapidly over com- 

 paratively dry substrata. 

 For this reason it has been frequently termed the " dry-rot fungus." 

 On account of its destructiveness to buildings in Europe it also goes 

 under the German name " Hausschwamm." It rots coniferous timber 

 for the most part. 



Coniophora puteana (PL VIII, figs. 5 and 6) resembles Merulius 

 lachrymans in color and general habit of growth. It is less gelati- 

 nous, however, and produces no porous strands. In some situations 

 it produces. a smooth, very thin, membranaceous layer on the surface 

 of timber; at other times the surface is quite warted or convolute. 

 The danger from th^ fungus is enhanced by its ability to rot hard- 

 wood as well as coniferous timber. 



Fig. 35. — Projecting ends of lumber which have de 

 cayed by coming in contact with the ground. 



