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APPENDIX A 



are known to be partly or completely dependent upon mycorrhiza are many 

 common forest trees such as oak, beech, and hornbeam, the famous heather of the 

 Scotch Highlands, certain ferns, and nearly all orchids. In some instances the 

 green plant may grow in the absence of the fungus, and vice versa; this is true of 

 certain of the forest trees and the fungi normally associated with them. 1 In other 



Fig. A. 8. Higher fungi (basidiomycetes) . Left, a stinkhorn, Dictyophora, the "egg" 

 stage above and the mature mushroom below; upper right, a puff ball, Lycoperdon perlatum; 

 lower right, an earthstar, Geastrum triplex. All belong to the puffball group. (Photos by 

 Prof. Alexander H. Smith.) 



instances the symbiotic relationship has become obligatory, neither the green 

 plant nor the fungus being able to exist alone. This is the case in many orchids, 

 and until this relationship was known, floriculturists had great difficulty in raising 

 these orchids in greenhouses. 



1 Among these fungi are many of the common forest mushrooms, such as Amanita 

 (most of the species of which are highly poisonous), Boletus, and Russula. These 

 mushrooms are the fruiting bodies of mycelial masses associated with, tree roots. 





