Ultrastructure and Analytical Microscopy of Silicon in the Leaf Cuticle of Ficus lyrata Warb.

Abstract

Leaves of Ficus lyrata contain large deposits of silicon (Si) in the adaxial and abaxial cuticles. Si was also found in the external and internal periclinal and anticlinal walls of epidermal and subepidermal cells. The Si in the cuticle filled large interstices that were sometimes confluent with each other and with the underlying cell wall material. Si deposits were more abundant in the adaxial than in the abaxial surface. Samples prepared without heavy metal stains showed that Si deposits have high intrinsic electron density. Sections incubted in 5% HFI had Substantially less Si than adjacent serial, nontreated sections. The Accumulation of the Si in the cuticle of F. lyrata is consistent with the proposed mechanism of apoplastic movement of monosilicic acid in the transpiration stream.