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Berlin-Heidelberg-New York: Springer.Įsau, K., 1977: Anatomy of seed plants, 2nd ed.

Protoplasma 100, 139–153.Įschrich, W., 1975: Sealing systems in phloem. P., Tsekos, I., 1979: Development of mestome sheath cells in leaves of Aegilops comosa var. T., 1977: The use of lanthanum to study the functional development of the Casparian strip in corn roots. W., 1970: Water pathways in higher plants. W., Platt, K., 1974: The apoplastic pathway of transport to salt glands. Liquid flow pathways and evaporative sites. W., 1976: Water movement into and through Tradescantia virginiana (L.) leaves. M., 1982: The suberin lamella, a possible barrier to water movement from the veins to the mesophyll of Themeda triandra Forsk.

H., 1971: Lanthanum as an intracellular stain.

The presence of Prussian-blue crystals and lanthanum deposits in the compound middle lamella of the radial wall of the bundle-sheath cells indicates that the compound middle lamella provides an apoplastic pathway for transpirational water from the xylem to the evaporating surfaces of the mesophyll and epidermal cells.īannister, L. Prussian blue and lanthanum deposits were abundant on the bundlesheath cell side of the bundle sheath/mesophyll interface but few occurred on that of the mesophyll, indicating that the suberin lamella is an effective barrier to apoplastic movement of both ferric and lanthanum ions. Judged from the distribution of Prussian-blue crystals (insoluble, crystalline deposits resulting from the precipitation of ferric ions by ferrocyanide anions) and lanthanum deposits, water and the tracer ions moved readily from the lumina of the vessels into the apoplast (cell wall continuum) of the phloem and bundle-sheath cells via portions of vessel primary walls not bearing lignified secondary wall thickenings. Two free-space marker procedures (Prussian blue and lanthanum nitrate) were employed to determine the pathway(s) followed by water and solutes in the transpiration stream after their introduction into the xylem of small and intermediate bundles, and the effectiveness of the suberin lamellae of the bundle-sheath cells as a barrier to the movement of tracer ions (Fe 3+ and La 3+).