DISTRIBUTION OF BASIDIOMYCETES 409 



species of Septobasidium is likewise restricted to the tropics. 

 Couch (1938) found that species occurring in the southeastern 

 United States are entirely different from those in the West Indies. 

 Moreover, some West Indian species are not found in Central 

 America and northern South America. Again, all those in Cuba 

 are distinct from those in Jamaica, except for 5. rhobarbarinum. 

 This species is indicated to be widely dispersed in Central Amer- 

 ica, tropical Africa, and the Orient. 



There is evidence that 5. pseudopedicellatum and S. curtisii, 

 common on many native species of trees and on cultivated ones 

 as well throughout the southeastern United States, may have been 

 introduced into other lands with shipments of trees. 



Distribution of other Basidiomycetes. Some impressions have 

 been recorded of comparative distribution of agarics in North 

 America and Europe by Lange (1934) and of the polypores in 

 these countries by Overholts (1939). Lange (1934) states that 

 70% of the species that he encountered on a tour across North 

 America were known also in Europe. He mentions certain species 

 that are common to both continents, such as Psalliota silvicola (P. 

 arvensis), Lactarius deliciosns, Pamis stipticus, Amanita muscaria, 

 A. caesarea, Hypholoma fascicular e, Inocybe geophylla, Laccaria 

 lac cat a, Stropharia psathyroides and Lepiota cygnea. The differ- 

 ence between the agaric floras of the two continents is in no wise 

 as striking as are differences on each continent due to latitude. 

 Stropharia depilata is a boreal species ranging from the Rocky 

 Mountains to the Scandinavian subarctic zone [Lange (1934)]. 

 Amanita caesarea is a temperate species and extends northward to 

 southern Denmark and northern Germany. Lange (1934) also 

 states that certain species in Europe are limited to the Mediter- 

 ranean region and rarely, if ever, extend beyond the Alps. Spe- 

 cies of Marasmius, some of which cause thread blights, and Lenti- 

 nus abound in the subtropics and tropics. 



Several well-known agarics, such as Clitocycbe ilhidens, Armil- 

 laria mucida, Colly bia radicata, and Lepiota procera, were noted 

 by Bisby (1933) as being absent from iManitoba for some un- 

 known reason. 



Certain agarics and Boletaceae are mycorrhizal, and some of 

 them are known to be restricted to certain species of trees. In 

 such cases the range of the tree is the factor which governs the 

 distributional range of the particular fungus. (See Chapter 13.) 



