Brief notes on the Internal structure of stem of Canna

A thin transuerse section of the young Canna stem shows the following internal structure from the surface to the centre.

(i) Epidermis:

Epidermis consists of a single layer of tangentially elongated, cutinized and compactly arranged cells.

(ii) Ground tissue:

It is the whole tissue that extends from the epidermal layer to the centre of the axis and in this tissue vascular bundles are embedded. It is not differentiated into hypodermis, endodermis and pericycle. It consists of the following regions.

Just below the epidermis 2-3 layers of compactly arranged parenchymatous cells are present.

Inner to parenchymatous layer, a few layers of chlorenchyma cells occur.

Isolated patches of sclerenchymatous cells are seen attached to the inner side chlorenchymatous layer. The rest of the ground tissue consists of thin walled parenchymatous cells.

(iii) Vascular bundles

Vascular bundles varying in shapes are distributed irregularly in the ground tissues. More number of vascular bundles is seen towards periphery. Peripheral bundles are smaller than the central bundles. Each vascular bundle is oval shaped and has a sclerenchymatous bundle sheath.

The vascular bundles are conjoint, collateral, end arch and closed. In the xylem there is a large Meta xylem element being surrounded by few protoxylem elements. Phloem is present on the outer part of the vascular bundle. It does not possess phloem parenchyma.