A comparative ultrastructural analysis of the fungal endophytes inCryptothallus mirabilisMalm. and other British thalloid hepatics

Many thalloid liverworts contain aseptate fungi forming arbuscules from swollen trunk hyphae within the host cells. Cryptothallus, Aneura and Riccardia are the only genera possessing basidiomycetous endophytes. The latter form extensive hyphal coils closely followed by the host plasma membrane, a situation mirroring the endomycorrhizas of orchids. The fungi in the subterranean gametophytes of pteridophytes exhibit behaviour similar to that in Cryptothallus but are almost certainly phycomycetes. It is tentatively suggested that the endophyte of Cryptothallus might be the same fungus as an ectrotroph of Betula roots.