Abstract:The ultrastructure of intranuclear inclusions in leaf mesophyll cells of Davidia involucrata was investigated with electron microscopy. Intranuclear inclusions occur generally in the cells of young and mature leaves. They consist of numerous bundles aggregated by several fibres (diameter about 10 nm), sometimes a few of bundles turn to tubules enveloped by fibres. Authors suggested that it is a new subtype (F2) of intranuclear fibrillar inclusion.