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Morphology and Histology of nirgundi - Vitex negundo Linn.

nirgundi :

nirgundi : Vitex negundo Linn.


Morphology:

Root:

  • Roots are woody, fairly thick, 8-10 cm in diameter; external surface brownish, rough due to the presence of longitudinal fissures and a small rootlets.
  • The bark is very thin and corky portion can be scrapped off easily.
  • Transverse section shows outer cork consisting of 12- 20 rows of nearly cubical to rectangular cells, the cells of peripheral rows being thick walled but not lignified.

Stem Bark:

  • Bark occurs in channelled pieces, 0.3- 0.5 cm thick; outer surface yellowish grey, rough, lenticelular, longitudinally channeled and transversely cracked;
  • inner surface darker than outer,
  • blackish and smooth; fracture short and splintery;
  • taste slightly bitter. In transverse section the bark
  • shows well developed periderm and secondary phloem elements.

Leaf

·         Leaves are palmately compound,

·         petiole 2.5-3.8 cm long;

·         3-5 foliate;

·          the middle leaflet is petiolate;

·         in trifoliate leaf, leaflet lanceolate or narrowly lanceolate, acute, entire or rarely crenate,

·         middle leaflet 5-10 cm long and 1.6-3.2 cm broad, with 1-1.3 cm long petiolule, remaining two subsessile;

·         in pentafoliate leaf inner three leaflets have petiolule and remaining two sub-sessile;

·         Odour is agreeably aromatic surface glabrous above and tomentose beneath; texture, leathery



Histology:

  • Petiole shows single layered epidermis having a number of unicellular, bicellular and uniseriate multicellular
  • covering trichomes and also glandular trichomes with uni to tricellular stalk and uni to bicellular head;
  • cortex composed of outer collenchymatous tissue and inner 6-8 layers of parenchymatous tissue;
  • collenchyma well developed in basal region and gradually decreases in middle and apical regions;
  • pericyclic fibres absent in basal region of petiole and
  • present in the form of a discontinuous ring in apical region surrounding central horse shoeshaped vascular bundle;
  • a few smaller vascular bundles present ventrally between arms of central vascular bundle and two, or rarely three, bundles situated outside the arms.

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