Kelley — 42 — Mycotrophy 



Amanita, so common in woodlands of Europe and eastern America, 

 has been studied, commencing with Boyer's (1915) observation that 

 the mycelia of many mushrooms, especially of Amanitas and boletes, 

 extend to mycorrhizae of neighbouring trees. A. muscaria seems the 

 principal mycorrhizal fungus of this genus, and was shown by 

 MoDESs (1941) to form mycorrhizae with pine and spruce. No less 

 than 17 species of Lactarius are said to be mycorrhiza-formers, and of 

 these L. delicosus and L. rufus are the chief, being confirmed by 

 synthetic experiment. All of these reports come from Europe, except 

 for three citations by Hatch (1937) for American material. Amer- 

 icans have listed three species of Clitocybe as mycorrhiza-formers, 

 but MoDESS, in synthesis experiment, reports none of the six species 

 he investigated as forming mycorrhizae. A considerable number of 

 species of Cortinarius are said to be mycorrhizal but detailed studies 

 are lacking in almost all cases ; and the same may be said for the 18 

 species of Russula that are alleged to form mycorrhizae. Tricholoma 

 has fared better, especially at the hands of Melin and Modess; but 

 the latter reports 4 species of the genus that failed to form synthetic 

 mycorrhizae. 



Some special cases among the Hymenomycetes may be cited. 

 The polypore Strohilomyces strobilaceus, a widely distributed 

 woodland species, was stated by Peyronel to be connected with 

 Coryliis Avellana. The Hydnums and most polypores one thinks of as 

 bracket fungi on wood, but Masui (1927) states that H. affine "was 

 determined" as a mycorrhiza-former with Pinus densiflora; Poly- 

 ucomelas was mycorrhizal also on this pine; while Long (1913) 

 stated that Polyporus Berkeleyi had been found on larch in Montana, 

 the fungus securing food from the forest humus, — which may or 

 may not have meant that the species was mycorrhizal. Amongst the 

 agarics one would suppose that Lepiota would surely be a mycorrhiza- 

 former, but MoDESS (1939) obtained uniformly negative tests in 

 attempting synthesis with species of this genus. Amanitopsis vag- 

 inata is mycorrhizal in Europe according to Peyronel and Modess. 

 The species is common also in America but is not reported mycorrhi- 

 zal. On the other hand, Cautharellus cibarius, which also occurs 

 both in Europe and America, is reported mycorrhizal only by Amer- 

 ican workers (Doak, 1934; Thomas, 1941.) Hygrophorus, having a 

 viscid cap, includes H. virgineus, which is mycorrhizal on spruce 

 (Frank, 1888), and H. Bresadolae and H. lucorum, on larch 

 (Peyronel, 1922). Omphalia, which we think of as tiny fungi of 

 damp leaf-mold, is mycorrhizal on Nothofagus in New Zealand ; and 

 the Fairy-ring fungus, Marasmius oreades, is mycorrhizal with Pinus 



