Structural Characterisation of the Leaf of Bauhinia monandra Kurz (Fabaceae - Cercidoideae)

Abstract Bauhinia monandra Kurz (Fabaceae) is an ornamental leguminous tree from Africa. Its leaf has been proven to be hypoglycaemic, and are a source of lecithin BmoLL, providing this species with great medicinal potential. Curiously, there are no reports of the anatomical description of the leaf of this species. The present work aimed at describing the leaf anatomy of B. monandra, and make histochemical inferences. To this end, anatomical procedures in light and scanning electron microscopy were performed from different parts of the leaves of plants growing in the state of Bahia, Brazil. The leaf is amphistomatous. It possesses papillate epidermis, nonglandular and navicular trichomes, and the mesophyll is dorsiventral. The central vein is distinct from the others of the first degree. The first, second, and third-degree veins possess thick fibre bundles with associated monocrystals. The other veins are a little fibrous and excessively reduced. The petiole vascularisation consists of circularly arranged collateral bundles, plus two accessory bundles. The pulvinus have a wide parenchymatic cortex with abundant druses and vascularisation restricted to the central region, surrounded by a crystalline sheath and by a starch sheath. The motile cushion has the vascular bundles arranged in series. Associated with the phloem from the pulvinus vascular bundles and the motile apparatus, occur non-lignified septate fibres that confer flexibility to these organs. The absence of lateral projections and the arrangement of vascular bundles in the petiole was the most distinctive anatomical features and of the greatest taxonomic potential observed in the leaf of B. monandra.