ECOLOGICAL CONSIDERATIONS 

 of many observations, that the Fungus cannot produce bruiting bodies 



without benefit of the in\corrhi/al relationship. To the mushroom col- 

 lector, the relationship between the kind ol tree and the mushroom 

 fruiting body is very important. 



Nearly all the species showing a probable mycorrhizal relation- 

 ship are found in the section Ht/grophOTUS. II. lu/pollicjus is associated 

 with 2- or o-needle pines; //. kauffmanu apparently w ith oak; //. pudo- 

 rinus with Abies and Picea (balsam and spruce I; and //. laricinus with 

 larch. There appears to be a true correlation between the degree of de- 

 velopment of the slimy outer veil and ability t<> form mycorrhiza. //. 

 camarophyUus and //. pudorinus are limited to conifers; and //. ago- 

 thosmus appears to be most frequently associated with spruce. Foi 

 many species the number of collections is not sufficient to allow accu- 

 rate conclusions to be drawn from them. In the mixed conifer-hard- 

 wood forests of Northern Michigan, or in the Great Smoky Moun- 

 tains National Park, it is often difficult or impossible to determine 

 which forest plants might be involved. 



Certain relationships between forest types and seasonal appear- 

 ance have been evident to students of Hygrophorus for a long time. 

 For instance, species of Hygrocybe would be expected to grow in July 

 and August in hardwood forests, especially in copses. Species of section 

 Hygrophorus would be sought in the conifer forests, and to some ex- 

 tent the hardwoods, after heavy autumn rains and the first frosts. This 

 temperature relationship undoubtedly explains why our mountain 

 conifer forests fairlv "blossom" with species of section Hygrophorus 

 when the fall rainy season sets in. 



The species of Hygrotrama which we have observed seem to occur 

 more frequently on naked, moist, but packed soil in what might be re- 

 garded as generally unfavorable habitats, but correlations are difficult 

 to establish. On the basis of the habitat data to date we would be 

 forced to conclude that //. suhjusccsccns has two forms, one occurring 

 at the edge of wood lots under hardwoods and specifically associated 

 with poison ivy, and the other on peat hummocks in cedar swamps. 

 We doubt that this species is so restricted. 



Sphagnum bogs are a good habitat for Hygrophori, especiall) the 

 H. miniatus — //. turundus complex. //. laetus, and //. nitidus. But our 

 luck in finding them has been best during hot, dry years when the wa- 

 ter level of the bog was reduced and the habitat had warmed con- 

 siderably. Cold, wet Sphagnum bogs are usually unfavorable for 

 agarics until the autumn fruiting of mushrooms, especially species of 

 section Hygrophorus. 



