Root systems of 8 Gymnostoma species, G. poissonianum, G. leucodon, G. webbianum, G., G. australianum, G. sumatranum, G. rumphianum and G. papuanum were sampled from various stands in New Caledonia, Australia and Malaysia. All six species exhibit nodule-like structure as recently described by Duhoux et al. (2001) in G. deplancheanum and G. nodiflorum. Histologically, these myconodules are all organized in the same way, with a central vascular cylinder and cortical cells intracellularly infected with fungal hyphae. Partial sequencing of nuclear small ribosomal of myconodules-extracted DNA identified the fungal partners as members of the glomales family. Glomus spores from soil extracts were purified and cytologically described. DNA extracts from these spores showed sequences similar to those of the myconodules. (Texte intégral)