1923] Fruit-body of New Parasitic Rhizopogon 107 



Rhizopogon parasiticus forms a compound ectotrophic mycorhiza; 

 but the mycorhizal character is short lived and the mass of inclosed 

 rootlets is completely absorbed. The fungus then forms its fruiting 

 surface right in the position that the obliterated pine tissues had held. 

 In the literature cited above we have found no reference to a fruit- 

 body formed in this way. Wolf (16) has shown that the Tuckahoe or 

 Indian-bread is formed by Poria Cocos attacking the pine root and 

 forming a large sclerotium within the bark of the root. Later, under 

 certain conditions, a poroid, resupinate fruit-body is formed on the 

 surface of the sclerotium. This Poria, though not a mycorhizal fungus, 

 does make an interesting comparison with our plant in that it replaces 

 much, though not all, of the pine tissue of the root. 



Summary 



1. A new fungus of the Hymenogastraceae is described and given 

 the name of Rhizopogon parasiticus, though doubt is expressed as to 

 whether the plant is correctly placed in the genus Rhizopogon or 

 whether it belongs to an undescribed genus. 



2. A review of the work on ectotrophic mycorhizas is given, and 

 Rhizopogon parasiticus is shown to form compound ectotrophic my- 

 corhizas on the roots of Pinus echinata and Pinus taeda. 



3. Rhizopogon parasiticus gives further proof of the parasitic 

 nature of ectotrophic mycorhizal forming fungi, for the pine tissues 

 of the rootlets invaded by this fungus are completely destroyed. 



4. The plant is unique in the way it forms the sporophore, form- 

 ing a gleba in the space formerly occupied by the invaded cluster of 

 pine rootlets. 



Chapel Hill, N. C. 



Literature Cited 



1. Bower, F. O. Botany of the Living Plant: 194-20-4. 1919. 



2. Bruns, E. Beitrag zur Keuutniss der Gattung Polysaccum. Flora 78: 67-75. 



1894. We take this reference from Groom for we have not examined this 

 paper. 



3. Cobb, C. The Forests of North Carolina. The North Carolina Booklet 12: 



136-157. 1916. 



4. Fischer, E. Hymenogastrineae. Pflanzenfamilien 1: 296-313. 1900. 



5. Frank, B. Ueber die auf Wurzelsymbiose bernhende Ernahrung gewisser 



Baume dureh unterirdische Pilze. Ber. Deutsch. bot. Gesellsch. 3: 128-145. 

 1885. 



