STRUCTURE AND HISTOCHEMISTRY OF THE FLORAL NECTARY OF <i>Bauhinia monandra</i> (FABACEAE)

Abstract

The structure and histochemistry of the floral nectary of Bauhinia monandra Kurz (Fabaceae) were investigated. Besides possessing medicinal properties, this tree is also used in the recovery of degraded areas and urban arborization. Nectaries samples were obtained from newly bloomed flowers. The nectary was located on the tubular hypanthium. This tube was partially coated by a nectary epidermis, whose cells had secretory features such as a relatively large nucleus, a dense cytoplasm, and small vacuoles. Subjacent to the nectary epidermis, there was a nectary parenchyma with eight to fifteen layers of cells which also have secretory features. Both the nectary epidermis and nectary parenchyma possessed starch grains. Subjacent to the nectary parenchyma passed collateral to amphicribral concentric vascular bundles constituted by more phloem than xylem. Although these vascular bundles did not emit terminations directed to the nectary parenchyma, the arrangement of the latter about the former suggests the supply of nectar precursors by the vascularisation. In the basal region of the hypanthium tube occurred modified stomata which were probably the main route of nectar release; and tector trichomes, possibly involved in the nectar retention.