INTRODUCTION 5 



radiatus are placed upon manure heaps the spores will germinate 

 at once and reproduce the plant in a day or two. 



Some of the perennial Polyporacecz continue to increase in size for 

 many years. The years of growth can be counted in the annual flesh- 

 strata, which are easily seen when sections are made. Mycelium will 

 continue to live in wood or in the ground for an apparently unlimited 

 time. I have known a " fairy-ring" of Clitocybe geotropa on Dunstable 

 Downs for forty or more years, which under favourable conditions of 

 light can be seen at a distance of more than a mile. The diameter 

 has not altered much during the time I have known it, for sometimes 

 it grows inwardly for several years and then again outwardly. 



Most species are terrestrial and grow on or just below the ground ; 

 a large number grow on dead leaves and twigs ; others on dead 

 wood, bark, branches and trunks. It is unusual to see fungi on 

 healthy trees; the majority of the larger fungi so commonly seen 

 growing on tree-trunks in parks, woods and forests are " wound 

 parasites," which germinate upon a damp injured place and grow 

 parasitically upon the living host. Rootlets are often attacked by 

 mycelium which at length develops as a perfect fungus at the 

 tree's base, as in Fames annosus^ or in other cases travels further up 

 the trunk as in F. igniaritis, and other species. Polyporus 

 Schweinitzii is well known to be highly destructive to conifers 

 Pinus StrobiiS) P. sylvestris and Larix europaa especially suffer. 

 Many other species of Polyporus are more or less destructive. 

 Amongst the Agaricacece, Armillaria mellea is one of the most 

 destructive ; it often grows upon living roots, not uncommonly under 

 the shade of large trees, the growth of the fungus being limited to 

 the extent of the root-growth of the trees. One form of its mycelium, 

 named Rhizomorpha^ lives perennially beneath the bark of trees. 

 It destroys tree-roots, chiefly those of conifers, but sometimes attacks 

 plum and other trees ; it also appears on squared timber, when 

 used for bridges, in mines, etc. 



Certain species grow parasitically upon other Basidiomycetes. 

 Volvaria Loveiana grows upon the pileus of Clitocybe nebularis ; 

 two species of Nyctalis grow upon the pileus or stem of species 

 of Russula and Lactarius ; and Boletus parasiticus grows from the 

 base or side of Scleroderma vulgare. Some species are almost 

 peculiar to human habitations : Coprimts radians grows upon 

 plastered walls, C. aphthosus commonly appears in kitchens and 

 cellars, Merulius lacrymans (Dry Rot), Poria hybrida and Polyporus 

 destructor are almost entirely confined to the interior of houses 

 and ships, and Merulius corium often grows in dwelling-houses. 

 Coprimis domesticiis is usually seen in or close to human dwellings ; 

 C. comatus and Cortinarius iirbicus commonly grow close to houses 

 or to places where human beings resort. Many species grow on 

 burnt wood and earth, as Clitocybe fumosa^ Collybia atrata, C. ambnsta, 

 Flammula decipiens, F. sapinea^ F. carbonaria, Lepiota Friesii^ Can- 

 tharellus radicosus^ Polystictus cinnamomeiis^ and many others. 



