Stem, Leaf and Root Anatomy of Eclipta alba (L.) Hassk. (Asteraceae)

Anatomical studies on transverse sections of stem, leaf and root were conducted under light microscope to find out identical characteristics of Eclipta alba (L.) Hassk, belongs to the Asteraceae family. Free hand transverse sections stained with safranin were studied here. In stem section, epidermis, hypodermis, endodermis, vascular bundle and pith characters were general without cortex. A number of air cavities setup scatteredly in cortex, where seen secretory structures closed to air cavities. Average diameters determined 34, 62, 20 and 92 µm in cortex, air cavity, metaxylem and pith cells, respectively. Amphistomatic leaf sections presented a relatively thick cuticle layer on the adaxial surface. Anisocytic stomata (19 ± 0.1 µm in diameter) at a large quantity in the abaxial surface, counted 4 stomata per µm2. The mesophyll was dorsiventral, composed of one layer palisade and four layers spongy parenchyma. The vascular system in leaf was open, collateral conjoint forming a flattened arch in the triangular shape. Secretory structure as single or group located laterally in the cortical parenchyma of leaf sections. At leaf blade side, upper epidermis, spongy and palisade cells showed 37, 33 and 74 µm diameter, respectively. Upper epidermis, cortex and metaxylem cells diameter at midrib were 12, 38 and 14 µm, respectively. In root section, the cortical zone (cortex cell 49 µm) was wide and a large region occupied with air cavities (72 µm) although other parts like epidermis (32 µm), endodermis and vascular bundle (metaxylem 23 µm) characteristics were standard. The thick cuticle on the adaxial surface of leaf is a special feature for the plant studied. The presence of air cavity in stems and roots suggested to adaptability in aquatic condition. The secretory structure in stems and leaves can be an identical character for the experimental plant as well as Asteraceae family