The effects of excess and deficient boron and niacin on vascular tissues of carrot roots (Daucus carota L. cv. Nantes) were investigated in plants grown in medium both rich and poor in boron and also boron with niacin. Five media were investigated: control (MS medium), boron-deficient MS medium, MS medium with excess boron, niacin-deficient MS medium, MS medium with niacin excess, and MS medium with excess boron and niacin. In anatomical cross sections, lignification was seen in middle lamellar pectins in the tracheary cells of boron deficit grown carrot roots, while in the other applications including excess boron lignification was in the secondary walls. Number of xylem arches and tracheary lengths of root cells were different, but not significantly so. Scanning electron microscopic (SEM) sections of vessels from roots grown in media with excess boron and deficient boron revealed paramural bodies in the tracheary walls. Paramural bodies were found in the tracheary cell walls of both boron deficient and boron excess grown carrot roots. In root cells grown in media with excess and deficient boron, tracheary cells had amyloplasts. While the boron deficient medium grown carrot roots had amyloplasts scarcely, in boron excess grown root cells these amyloplasts filled the vessels densely.