Survey of histo-anatomical features of vegetative organs in the Hedera helix L. (Araliaceae)

Hedera helix L. (Araliaceae) is a climbing plant, the stem and leaves of H. helix possess specific features in accordance with its climbing nature. Hedera has two types of fertile and sterile stems. A thick cuticle covers the epidermis, multicellular trichomes for the protection of plant are present on the stem surface, petiole and blade. For investigated histo-anatomical characteristics of the vegetative organs, samples of leaves and stem prepared manually transverse sectioned. All samples were cleared in 20% sodium hypochlorite then stained in methyl blue and acetocarmine, analysis using a light microscope. The stem has a secondary structure, thickenings due to the function of a cambial ring. Cork cambium is also present, at first superficial, forming a cylinder (circular ring in cross-section) around the stem. The cortex is severely reduced, which consists of 3-4 layers of parenchymal cells. The stele occupies the wide part of the stem. The mechanical tissue is poorly developed and possess of septate fiber bundles in the stem, but it is well developed in the petiole, being displayed by collenchymatous cell layers, the stele consists of three vascular bundles. Bundle sheaths are absent in the blade and petiole, the hardness of blade is given by collenchyma cells located in between the middle vein and the two epidermises. There are a number of calcium oxalate cavities in each stem and leaf duct (particularly around the middle veins). Secretory cavities are present in both stem and blade, but the petioles lack them.

کلیدواژه ها:

Cork cambium ، methyl blue ، middle veins ، collenchymatous