EN
The development and (ultra)structure of vascular tissue was studied in Lupinus luteus L. mature root nodules 25 and 60 days after inoculation. In the proximal part of the nodule vascular trace, extensive growth took place to match the secondary growth of the root. Development of bacteroid and vascular tissues was correlated. The non-anastomosing nodule vascular bundles elongated and branched due to the activity of nodule lateral meristems, thus forming an extensive vascular network within deep lobes of bacteroid tissue. The vascular trace and vascular bundles differed mainly in the location and ultrastructure of transfer cells and parenchymatous cells, in which the inner membrane of the nuclear envelope formed tubular invaginations within the dense chromatin. Development of the vascular system in the collar root nodule of lupine differed from that of cylindrical indeterminate nodules.