Lecture VII — 95 — Mycothalli and Mycorrhizomes 



Ferns gives a longer description ; he found infection also in prothallus 

 of Osmitnda cinnamomea. In 1908 he stated that he had found an 

 endophytic fungus normally present in green prothalli of several 

 Marattiaceae, Osmiindaccae and Gleicheniaceae. The endophyte con- 

 sisted of large, branched non-septate hyphae w^hich are strictly intra- 

 cellular. Vesicles and apparent digestion stages are described, and in 

 figure ten there is shown a vesicle near an intact nucleus. In 1921, 

 Campbell said than an endophytic fungus occupies a large part of 

 inner tissue of gametophyte of Botrychiuni ohliqimm, but in older 

 gametophyte it does not invade tissues about reproductive organs. The 

 fungus fills lumen of cells but nucleus remains intact. The myco- 

 thallus of B. lunaria is described by Bruchmann (1906), infection 

 taking place usually through rhizoids although it may occur directly 

 through surface of the prothallus. Outer cells are at first invaded but 

 later the fungus leaves them and is confined to middle and basal cells 

 which have large nuclei and fungal clots. Starch is present only in 

 meristem and in cells about reproductive organs while in those cells 

 which have no starch the hyphae are filled with oil and protein. The 

 advantage of mutualistic life of fungus and prothallus seems to con- 

 sist in a holding and storing of reserve, especially oil, which is of value 

 during summer heat and winter cold in protecting the prothallus from 

 drying. The endophyte is present in every prothallus, living in all 

 the inner and radially formed outer portion. 



Stokey (1942) found no infection of gametophyte of Marattia 

 or of Macroglossum grown on sterilized peat, growth being vigorous 

 and "normal". The structure of Hehninthostachys zeylanica prothalli 

 is essentially similar to that of Ophioglossmn (Lang, I.e.) The cells 

 containing vesicles seem healthy but starch is usually absent from 

 them. The fungus is healthy until growth of the sexual portion of 

 the prothallus commences, whereupon the fungus dies and the pro- 

 thallus develops up to the extent of the amount of reserve material. 

 In prothalli of the fern Cheiropleuria, Nakai (1933) found fungal 

 hyphae which entered by way of brown rhizoids and filled the median 

 part of the prothallus where they branched and coiled to form a 

 nutritive layer. The median layer is stimulated by presence of fungus 

 to form 5-10 layers of cells. Uninfected prothalli were also observed 

 and Nakai thought these may have been sterile or male. 



Mycothalli in Lycopod Gametophytes: — Following Treub's 

 discovery of endophytism in a Javan lycopod, Bruchmann (1885) 

 described fungal structures in prothallus of Lyeopodium; and in 1898 

 said that a Pythium sort of a fungus occurs in palisade and cortical 

 layers of L. elavatum and L. annotinum, and is also found in rhizoids 



