Morpho-anatomy of the leaf of Myrciaria glomerata

Myrciaria glomerata O. Berg., Myrtaceae, popularly known as “cabeludinha”, has high content of ascorbic acid and anti-inflammatory property and is used in folk medicine. The objectives of this study were the morphological, anatomical and histochemical characterization of the leaves. Leaf studies were made with optical, scanning electron and confocal microscopy. The collection of botanical material was held at the Tijuca Forest, Rio de Janeiro, RJ. Histochemical tests aimed the identification of lipids, starch grains, phenolic compounds and crystals. The leaves are simple, opposite, lanceolate, pinnate, hairy, with involute margins, hypostomatic and dorsiventral. The stomata are anomocytic. The epidermis presents simple trichomes. Epidermal cells show uneven thickening of their periclinal outer walls, mainly on the adaxial side of the leaf. Secretory cavities of essential oils are subepidermal and exceed, in height, the palisade parenchyma, formed by one cell layer. Four to five cellular layers, rich in phenolic compounds and lipids form the spongy parenchyma. The bundles are collateral and there are many crystals of calcium oxalate spread throughout the mesophyll. In the midrib and petiole the bundles are bicollateral. Analysis by scanning electron revealed epicuticular wax rod-shaped and as grains. In confocal microscopy, the adaxial epidermis, the fibers and the secretory epithelium of the cavities show autofluorescence. The data obtained are important in quality control exams of samples of this species.

Myrciaria glomerata O. Berg – (a) Leaves with incurved margins and ripe yellow fruits. (b) Epidermal surface of the adaxial side of the leaf in OM. (c) Surface of the adaxial side of the leaf in SEM, showing the secretory cavity (clustered) and the scattered granules of epicuticular wax. (d) Cross section of midrib stained with astra blue and safranin. Note the vascular system configuration. (e) Confocal microscopy, showing the midrib. It is visible the autofluorescence of the fibers, cuticle and the epithelium of the secretory cavity. (f) Positive histochemical test of starch grains in the petiole (arrows).Figure optionsDownload as PowerPoint slide