70 BRITISH FUNGI 



on the attachment of the gills to the stem, into three groups 

 belonging respectively to the genera Tricholoma, Cliiocyhe, and 

 Collybia. 



The species grow on wood ; tliey frequentl\- appear to grow on 

 the ground, but if carefully examined it will be found that the 

 mycelium originates from buried wood, roots, etc. Some species, 

 as A. melleiis, are very destructi^•e parasites, and spread from tree 

 to tree by means of underground mycelium. None are edible or 

 certainly not worth eating, although A. melleiis and A. mucidiis are 

 sometimes recommended. 



TricJwloma 



This is one of the genera containing a large number of species 

 characterized more especially by the sinuate gills. The species are 

 mostly of large size and robust build, having a fairly thick, fleshy 

 cap and short, stout stem. No trace of ring or volva is present. 

 The cap is often scaly, the scales usuall}- being adpressed or flat- 

 tened and adhering to the cap. In other cases the cap is viscid, 

 sometimes glutinous. The stem is usually sohd and fibrous through- 

 out, that is, it is composed of a compacted bundle of longitudinally 

 arranged strands or fibres. This structure is apparent on the out- 

 side, hence the stem is described as fibrous, as opposed to those 

 fungi having the stem corticated or polished on the outside and 

 showing no fibrous structure. The gills vary considerably in colour, 

 being white in some species, dark grey in others, and yellow in a few 

 species. The sinuation of the gills is ver\' marked in many species, 

 in others the character is but vaguely indicated. The spores are 

 white in all species independent of the colour of tlie gills. 



TricJioloma is closely allied to the following genera. Species 

 of Pleurotus having the stem central are mainly distinguished by 

 growing on wood. Collybia differs in the corticated or polished 

 stem. Clitocyhe is distinguished by the gills never being sinuate, 

 and always more or less decurrent. 



All the species, with one or two exceptions, grow on the ground ; 

 the majority appear in the autumn, but a few of the larger species, 

 as St. George's mushroom, T. gambosum, an edible species, appear 

 in the spring. Some species, as 7\ siiljureum, have a ver\' un- 

 pleasant smell. In many species the gills become spotted or stained 

 with brown or rust colour. 



. Russiila 

 A very large genus of fungi, and one which cannot be mistaken 

 when the features are once grasped, but they are perhaps somewhat 

 difficult to convey in writing. The species are generally large and 

 stout, very rigid, the flesh of the cap is thick, compact, and firm, 

 the stem is stout, short, and never perfectly hollow, altliough in some 

 species it is described as being stuffed, which means that the central 



