FUNGI: BRACKET FUNGI 



327 



peeled into thin strips and made into garments by peasants of 

 some European countries. In some species there are several 

 rings formed each year on the surface so that this will not indi- 

 cate the age, as in the 

 flattened bracket fungus, 

 so often used for sketch- 

 ing or writing on the 

 under surface. But the 

 age of this fungus can be 

 determined by splitting it 

 in two along the middle, 

 since there is one stratum 

 of tubes formed each year 

 on the underside. Some 

 of the bracket fungi are 

 annual, that is, they die 

 during the same season 

 in which they are formed, 

 but the mycelium may live 

 in the trunk many sea- 

 sons, a century or longer, 

 every now and then pro- 

 ducing new fruit bodies. Many of these bracket fungi are 

 called wood-destroying fungi, because the action of the mycelium 

 is so destructive to timber (see paragraph 217). Some of them 

 are called "wound" parasites, since they can only enter living 

 trees through a wound in the cambium layer, or when a limb is 

 broken off, or carelessly pruned. The heart wood being dead 

 the mycelium can then enter, and produce heart rot, thus destroy- 

 ing the timber and weakening the tree and its roots. Many of the 

 pore fungi are not bracket forms. Some are spread out on the 

 surface of wood, and many have a cap and central stem. The 

 largest number of those with central stem are quite large fleshy 

 fungi belonging to the genus Boletus. Some of these are edible 

 as the " Steinpilz " of Germany, or the " cepes " of France (Bole- 

 tus edulis). Some are said to be poisonous. Many have bright 



Fig. 287. 



Pine inhabiting Polyporus (Polyporus pinicola) 

 growing on fallen hemlock log. 



