CHAPTER V 



FOMES APPLANATUS AND ITS SPORE-DISCHARGE PERIOD 



Habitat and Hosts A Wound Parasite Spore Structure The Longevity of the 

 Fruit-body The Longevity of Various Polyporeae The Hymenial Tubes 

 The Spore-discharge Period A Comparison of the Spore-fall Period of Certain 

 Hymenomycetes The Mechanical Consistence of Coprinus and Fomes Fruit- 

 bodies Contrasted The Number of Spores in Fomes applanatus and Other 

 Basidiomycetes The Cause of the Long Spore-discharge Period in Fomes 

 applanatus The Progressive Exhaustion of the Hymenial Tubes The 

 Significance of the Production of Vast Numbers of Spores 



Habitat and Hosts. The fruit-bodies of Fomes applanatus have 

 been found upon upwards of fifty species of trees included in the 

 following genera : (Dicotyledones) Acer, Aesculus, Alnus, Betula 

 (Fig. 43), Carpinus, Crataegus, Fagus, Fraxinus, Gleditschia, 

 Hicoria, Liriodendron, Malus, Morus, Nyssa, Populus, Prunus, 

 Pyrus, Quercus, Robinia, Salix, Tilia, Ulmus, and Umbilicaria ; 

 (Coniferae) Abies, Picea, Pinus, Pseudotsuga, and Tsuga. 1 The 

 fungus causes the decay of very large quantities of wood annually 

 and must be considered as one of the most destructive of wood- 

 destroying agencies. 



A Wound Parasite. J. H. White has recently shown that 

 -Fomes applanatus, when growing on living trees, is not a sapro- 

 phyte, but is a wound parasite, i.e. a fungus which invades a tree 

 via some exposed wound and which then progressively enters, kills, 

 and destroys the living tissues of its host. His proof of parasitism 

 is based on three arguments, the second of which appears to be not 

 only novel but also conclusive. These arguments are as follows. 



1 G. G. Hedgcock, " Notes on Some Diseases of Trees in our National Forests," 

 Phytopathology, vol. ii, 1912, p. 75 ; also vol. iv, 1914, p. 185. Also J. H. White, 

 " On the Biology of Fomes applanatus," Trans. Roy. Canadian Institute, Toronto, 

 1919, p. 136. Hedgcock records 53 species attacked by the Fomes, and White 21. 



