MYCORRHIZA-LIKE INTERACTION BETWEEN THE ACHLOROPHYLLOUS GAMETOPHYTE OF LYCOPODIUM-CLAVATUM L AND ITS FUNGAL ENDOPHYTE STUDIED BY LIGHT AND ELECTRON-MICROSCOPY

The mycorrhiza-like association of mature gametophytes of Lycopodium c lavatum and an endophytic fungus was studied by means of light and ele ctron microscopy. Fine aseptate hyphae of the fungus formed very regul ar dense hyphal coils and numerous small vesicles of different stages in the cortical cells. Extended infections occurred within preformed s paces between the cells of the storage tissue. These spaces probably a rose by degeneration of the host cells. Several hyphae grew within the m and were partly swollen or irregularly lobed and branched. They were embedded in a heterogeneous material, probably of host origin. Arbusc les were not established during the interaction. All fungal structures degenerated in the older host tissues that remained intact. The fungu s contained bacterium-like organelles. Elliptic interphase spindle-pol e bodies of the fungus were attached to the outer nuclear envelope. Th e host-fungus interaction in the gametophyte of L. clavatum cannot be related to any type of mycorrhizal association described to date. It i s therefore called the 'Lycopodioid mycothallus interaction'.