Anatomical Features of Tinospora cordifolia

Observations

The transverse section of the stem of Tinospora cordifolia shows a more or less circular outline. The internal tissues are differentiated into cork, cortex, pericycle, vascular tissues, medullary rays and a large central pith.

1. Cork or Periderm

The outermost region of an older Tinospora stem consists of several layers of cork cells. These cells are compactly arranged and provide protection to the internal tissues. The cork becomes well developed as the stem undergoes secondary growth. The outer bark of an old stem therefore appears rough and fissured.

2. Cortex

Below the cork lies the cortical region. The cortex is comparatively broad and is mainly composed of parenchymatous cells. These cells may contain reserve food materials In younger portions of the stem, the outer cortical region may contain chlorenchymatous cells containing chloroplasts. The cortical tissues gradually merge into the inner region.

3. Pericycle

The pericycle occurs towards the inner side of the cortex. It is characterized by patches or groups of sclerenchymatous fibres. These fibres possess thick and lignified walls and provide mechanical strength to the climbing stem.

4. Vascular System

The vascular system is highly developed. The vascular tissues occur in the form of distinct vascular bundles arranged in a ring.The vascular bundles are conjoint, collateral and open. Phloem occurs towards the outer side, while xylem is present towards the inner side. A strip of vascular cambium is present between the phloem and xylem.

5. Phloem

The phloem is situated outside the cambial region. It is composed mainly of sieve elements, companion cells and phloem parenchyma. The phloem conducts prepared organic food from the leaves to other parts of the plant. In older stems, secondary phloem becomes well developed as a result of cambial activity.

6. Cambium

A cambial zone is present between the secondary phloem and secondary xylem. It consists of actively dividing meristematic cells. The cambium produces secondary xylem towards the inner side and secondary phloem towards the outer side. Therefore, the cambial activity is mainly responsible for the increase in thickness of the stem.

7. Xylem

The xylem occupies a large portion of the vascular region. It is composed of vessels, tracheids, fibres and xylem parenchyma. The xylem vessels are prominent and comparatively large. They are responsible for the conduction of water and dissolved mineral salts from the roots to the aerial parts of the plant. Secondary xylem becomes extensive in mature stems because of secondary growth.

8. Medullary Rays

Broad and conspicuous medullary rays occur between the vascular regions. They extend radially from the pith towards the cortex. The medullary rays are composed mainly of parenchymatous cells. They are involved in the radial transport of water and food materials and also act as storage tissues. The presence of broad medullary rays is an important anatomical feature of Tinospora stem.

9. Pith

A large and well-developed pith occupies the central portion of the stem. It is composed of thin-walled parenchymatous cells. The cells of the pith mainly perform storage functions. In older stems, the pith may become comparatively less compact.

Identifying Anatomical Features of Tinospora

The major identifying anatomical features of the stem are:

1. Well-developed cork in older stems
2. Broad parenchymatous cortex
3. Sclerenchymatous patches in the pericyclic region
4. Vascular bundles arranged in a ring
5. Conjoint, collateral and open vascular bundles
6. Well-developed cambium
7. Extensive secondary xylem
8. Large and prominent xylem vessels
9. Broad medullary rays
10. Large central parenchymatous pith
11. Well-marked secondary growth in mature stems