Anatomy of hydathodes and pigment disks in leaves of Ficus diversifolia (Moraceae)

Abstract

In Ficus diversifolia, “mistletoe fig”, hydathodes are scattered over the leaf lamina. They open to the adaxial surface via a circular, slightly depressed epidermal pad studded with 20–30 water pores. The epithem is a cylinder of small cells, irregular in shape, with conspicuous intercellular spaces, bounded by a close-fitting sheath of unpigmented cells. Hydathodes occur above characteristic junctions of three or more minor veins, from which short tracheary strands extend upward into the epithem and end blindly. Phloem does not seem to be involved. Unsuccessful attempts were made to induce guttation. Red pigment spots occur abaxially in the axils of major veins. They are compact internal disks of parenchyma cells containing granules of various sizes. A vascular bundle arches downward, passes over the disk, then curves upward to rejoin other bundles. The central large disk has a palisade epidermis of slender elongate cells separated from each other by cuticle; the other disks have a normal epidermis.