LEAF: DATURA - EXPERIMENT

     LEAF: DATURA

AIM:

To study the histological characters of  Datura leaf.

Requirements:

Chemicals:

Chloralhydrate solution, Phloroglucinol solution, conc. HCl, glycerine.

Glasswares:

Micro slides, cover slips, compound microscope, watch glass.

Description:

TS of Datura leaf is devided in to 02 regions

1. Lamina region

2. Midrib region

1.LAMINA REGION

Upper epidermis: The upper epidermis is covered with a smooth cuticle

It has single layered cells rectangular with cuticularized outer walls.

Upper eoidermis has number of stomata and trichomes.

Stomata: Anisocytic or cruciferous type of stomata is present, in which 3 subsidiary cells surrounds 2 guard cells, in which one of the subsidiary cell nis smaller than the other two.

Trichomes: Both covering and glandular trichomes are seen.

Covering trichomes are uniseriate, multicellular, warty and blunt at the apex.

Covering trichomes have 3 to 5 celled uniseriate stalk where as it is 8 celled in datura herb.

Glandular trichomes are are also called as non covering trichome

They are uniseriate, 1 to 2 celled made up of stalk of one cell and 2 to 4 celled glandular head.

Mesophyll:

Mesophyll is differenciated in to palisade and spongy parenchyma.

Palisade:

Palisade cell is made up of elongated cells.

This layer is found only beneath the upper epidermis . below the palisade layer a crystal layer

( of 1 cell thick) is present.

Each cell of the crystal layer contains calcium oxalate clusters.

Spongy parenchyma: It consists of  many loosely arranged cells with intercellular spaces.

These cells contains abundent calcium oxalate crystals, which occur either as prisms or  microsphenoidal sandy crystals.

Number of idioblasts are found in spongy parenchymatous tissue.

Vascular strands are found in the upper layers of spongy parenchyma.

Lower epidermis:

It is similar to upper epidermis, lower epidermis is covered with smooth cuticle.

Anisocytic stomata is found in larger proportion than the upper epidermis

Both covering and glandular trichomes are also found.

2.MIDRIB REGION

The midrib region of the leaf is consists of following regions.

1.      Collenchymatous tissue

2.      Vascular bundles

3.      Endodermis

1.      Collenchymatous tissue:

The collenchymatous tissue which is abundent is made up of hypodermal collenchyma cell.

The collenchymatous cells are found on both the surfaces of the midrib.

2.      Vascular bundles:

The vascular bundle comprises of xylem and phloem. Bicolateral (xylem in the center surrounded by phloem on either side) type of vascular bundle is present. The xylem is present in an arc.

3.      Endodermis:

Endodermis is made up of thin walled parenchyma cells which are compactly arranged. The enodermis forms a covering sheath around the vascular bundles, it contains numerous starch grains.

Allied drugs:

Datura innoxia:

Leaves are oval with entire margin

Datura tatula:

Leaves are smaller

Covering trichomes are generally longer petiole gives pink colour with HCl