Kelley — 44 — Mycotrophy 



As early as 1847, Reissek was isolating a fungus from the "root" of 

 Orchis Morio which he assigned to this genus and named F. endor- 

 rhisinn; while, in 1890, Vuillemin cites a Fusariiim from O. mascula; 

 in 1900, Bernard, from Ophioglossum vttlgatmn. In 1901, Bernard 

 said that tuber-formation in the potato is called forth by an endophy- 

 tic fungus, F. solani. The fungus is now generally distributed in 

 European soil and potatoes form freely, but at first potatoes grown 

 from seed did not form tubers until the soil was inoculated with 

 fungus. The next year Bernard stated that the fungi concerned in 

 all tuber-formation are Fusarium spp., conidial forms of which are 

 near to the related genera of Nectria and Hypomyces except that 

 the fungus of potato is F. solani. But, in 1904, Bernard decided that 

 the Fusaria often obtained from orchids are not the specific fungi 

 since they do not cause germination ; and the endophyte, he decided, 

 as obtained from Cattlyea is a fungus described by Bernard as 

 "Mucedinee oosporee." The following year he said that, while the 

 endophyte of Cattlyea has structures similar to those of Oospora, 

 that from Odontoglossum grande is similar to RJiisoctonia; and to 

 Rhisoctonia Bernard adhered during the rest of his brief life. 



Rhizoctonia : — The sterile fungus, Rhisoctonia, which in one case 

 at least (Sprau, 1937) is identified with Corticinin, has been much 

 talked of since the days of Bernard ; indeed, many botanists had the 

 idea that study of mycorrhizae was largely the study of these fungi. 

 Most of the fungi isolated from orchids in those days were identified 

 as species of Rhisoctonia, for example: R. languinosa (Bernard, 

 1909), R. Goodyerae repentis (Costantin, 1920), etc. More recently 

 other species have been cited, as R. repens (Knudson^ 1925), R. 

 mucoroides (Porter, 1942). 



Phoma: — The genus Phoma, with conidiospores in pycnia in- 

 stead of on conidiophores as in the Rhizoctonias, has been cited a 

 number of times. Ternetz (1907) studied five species assigned to 

 this genus, which she isolated from native German Ericaceae; while 

 Rayner (1915) found a fungus in Calluna which she placed in a new 

 genus, Phyllophoma, since it occurred not alone in the root but 

 throughout the whole plant. From Vaccinium Oxycoccos, Addoms 

 (1931) isolated Plwma radicis. But in his study of root fungi of Vac- 

 cinium, Freisleben (1934), who isolated the mycorrhizal fungi, said 

 that they were apparently not to be referred tO' the genus Phoma, to 

 which other authors had assigned the endophytes of the Ericaceae. As 

 to other plants: P. R. White (1929) separated several fungi from 

 mycorrhizae of Fragaria and thought that a Phoma was responsible 



