Fine endophytes (FE), Glomus tenue, are traditionally considered to be arbuscular mycorrhizal fungi (AMF) with distinctive microscopic morphology when stained. FE have fine hyphae (c. 1.5 lm diameter) which branch intra-cellularly in a distinctive fan-like pattern (Gianinazzi-Pearson et al., 1981; Abbott, 1982). The hyphae contain small swellings along their length, sometimes referred to as vesicle-like swellings (Hall, 1977). FE form arbuscules (or arbuscule-like structures) with fine elements in a tapered, conical shape (Greenall, 1963; Merryweather & Fitter, 1998). Spores of FE are very small (< 20 lm) compared to the majority of Glomeromycota, and colourless (Hall, 1977). Morphological variations indicate that FE may consist of multiple species (Thippayarugs et al., 1999), hence we use the term FE to indicate a species group.