HYDNUM. 



433 



Hydnum Schiedermayeri Heufl. (U.S. America). Sporo- 

 phores fleshy, with a sulphur-yellow colour both outside and 

 inside, and with a smell of anise. They occur on living 

 apple-trees, less frequently on other species of Pyrus. Accord- 

 ing to Schroeter, Thiimen, and 

 Ludwig, the mycelium spreads 

 through the stems and kills 

 the trees. 



Thumen ^ thus describes the 

 diseased wood of the apple: "It 

 has a greenish-yellow colour, 

 which passes over gradually 

 to the normal colour of the 

 wood : it becomes soft and 

 friable, smelling, like the 

 sporophore, faintly of anise." 



Sistotrema fusco-violaceum 

 Schrad. (Britain.) This according 

 to Skiljakow^ is parasitic jan living 

 pines, entering by wounds, and 

 carrying destruction throughout 

 the wood. 



POLYPOREAE. 



Polyporus. 



Sporophores large and 

 usually shaped more or less 

 like a hoof or small bracket. 

 The sporogenous layer is com- 

 posed of cylindrical tubes, 

 which generally occupy the 

 lower surface of the sporophore. 



The substance between the tubes is different from that of the 

 rest of the sporophore. 



Polyporus (Femes) igniarius (L.).^ (Britain and U.S. America). 

 Sporophores on living stems of oak, alder, apple, willow, and other 



^Thumen, " Ein Apfelbaum-Schadling." Zeitsch. f. Pflanzenkranhheiten, 1891. 

 ^Skiljakow, Scripta botan. horti universitatis Petropolitanae, 1890. 

 *R. Hartig, Zersetzungserscheinungen, PI. XV. and XVI. 



2e 



Fig. 263. — Polyporus igniarius on Oak. At 

 the upper end a wood-pecker's nest-hole. (v. 

 Tubeuf phot.) 



