The Occurrence of Silica in the Leaves of Magnolia grandiflora L.

The "glistening" bodies observed at the foliar veinlet termini, epidermis, and vein sheath in Magnolia grandiflora L. contain silica. The silica was studied by light microscopy, transmission electron microscopy, scanning electron microscopy, and energy dispersive X-ray microprobe analysis as isolated particles (phytoliths) and in sectioned leaves. The silica is amorphous and is composed of roughly spherical bodies (35-65 nm) that form in the lumen of terminal tracheids, vein sheath cells, epidermal cells, and guard cells. Silica is also found as a layer exterior to the cell wall of epidermal cells and in the cuticle. In the leaf, silica deposition may function to strengthen the leaf, reduce transpiration, and increase resistance to pathogens.