BARK: CASSIA BARK - EXPERIMENT

BARK: CASSIA BARK

AIM:

To study the histological characters of  Cassia bark.

Requirements:

Chemicals:

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

Glasswares:

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

Crude drug:

Cassia bark

Description: TS of the cassia is broadly described into Periderm, Cortex, a band of sclerenchyma and secondary phloem. Epidermis and cork are completely absent.

Periderm: cork- Few layers of which the outer one are with thin walls and the inner ones are lignified and thick walled.

Phellogen and phelloderm can not be distinguished either from each other or from the cork.

Cortex:

It consists of 10 to 15 layers of parenchyma in which sclerides are scattered isolated or in groups. Each scleride is rectangular and pitted with thickened inner and radial walls. Some of the parenchymatous cells contains minute acicular raphides and abundant starch.

Sclerenchymatous band or Stone cell layer:

A continuous belt of sclerides occurs in between the primary cortex and secondary phloem.

The sclerides which are lignified and pitted are typical characteristic of cassia bark.

The inner and radial walls of sclerides are more thicker than the outer walls giving the appearance of the letter “U” on the outer side of sclerenchymatous band are found a few groups of small pericyclic fibres.

Secondary phloem consists of phloem parenchyma, phloem fibres and medullary rays.

Phloem parenchyma consists of thin walled cells containing abundant starch grain, minute acicular raphides.

Number of big isolated oil cells are seen in phloem parenchyma which is another characteristic feature of cassia bark.

Phloem fibres occurs mostly single or isolated rarely in groups of 2 to 3, embedded in phloem parenchyma.

Fibres are circular and lignified and stratification.

Medullary layers are 1 to 3 cells wide and externally extended up to stone cell layer where they become wider rays also contains starch grains and acicular raphides.