In the roots of most species of terrestrial and epiphytic Malayan orchids examined, mycorrhizal infection was spasmodic and confined to a small proportion of the root cortex cells. Only a few terrestrial species exhibited the pattern of dense infection seen in north temperate orchids. Chlorophyllous tissue in the roots of some terrestrial and epiphytic species was invaded and cytological changes, including fragmentation and disappearance of the chloroplasts, occurred in some instances.

Measurements of host cell nuclei indicated that nuclear hypertrophy occurred not only in infected cells but also in many non-infected cells localized around pockets of infection.