Preparation of T.S of bignonia steam
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Anatomy of Bignonia – Stem (Family – Bignoniaceae):
T.S. shows many ridges and furrows and reveals the following tissues from outside with-in:
Epidermis:
1. Single-layered epidermis consists of rectangular cells.
2. A thick cuticle is present.
3. A few multicellidar hairs are also arising from some cells.
Cortex:
4. Ii is well-differentiated into collenchyma and parenchyma.
5. Collenchyma is present below the epidermis in the ridges in young stem but at maturity there develops sclerenchyma.
6. Parenchyma is present below the sclerenchyma or collenchyma in the ridges and directly below the epidermis in the grooves.
7. In old stem cortex consists of cork, cork cambium and cortex.
8. Endodermis is undistinguishable from cortical cells. The cells lack casparian strips.

Pericycle:
9. It is in sclerenchymatous patches.
Vascular system:
10. It phloem, secondary phloem, xylem and primary xylem.
11. Four longitudinal furrows of secondary phloem arc present which are wedged in between the secondary xylem cylinder.
12. Vascular bundles are conjoint, collateral, open and endarch.
13. Primary phloem is crushed and present in small patches.
14. Secondary phloem is in the form of a ring which remains intruded into the secondary xylem at four places.
15. Intruded furrows (four) of secondary phloem are arranged in the form of a cross.
16. In Bignonia unguis-catae, bars of sclerenchyma are present in the furrows of secondary phloem.
17. Cambium is single layered, present in between xylem and phloem and bent towards inner side along the furrows of secondary phloem.
18. Secondary xylem consists of vessels, tracheids, fibres and xylem parenchyma.
19. Due to the intrusion of the phloem at four places, secondary xylem is ridged and furrowed at four places.
20. Primary xylem is present close to the pith facing its protoxylem towards the centre. Its location is just opposite to the patches of primary phloem.
Pith:
21. It is thin walled and parenchymatous.
Secondary Growth:
Formation of four furrows of secondary phloem in the secondary xylem is due to the abnormal functioning of cambium which was behaving normally sometimes earlier.
At four or more places cambium produces less amount of secondary xylem towards inter side and large amount of secondary phloem towards outer side. Thus four wedges of secondary phloem are formed. They intrude into the secondary xylem and so xylem cylinder appears ridged and furrowed.
Identification:
(a) 1. Presence of vessels in the xylem. (Angiosperms)
(b) 1. Multicellular epidermal hairs.
2. Conjoint, collateral, open and endarch vascular bundles. (Stem)
(c) 1. Vascular bundles in a ring.
2. Presence of cambium. (Dicotyledones)
T.S. shows many ridges and furrows and reveals the following tissues from outside with-in:
Epidermis:
1. Single-layered epidermis consists of rectangular cells.
2. A thick cuticle is present.
3. A few multicellidar hairs are also arising from some cells.
Cortex:
4. Ii is well-differentiated into collenchyma and parenchyma.
5. Collenchyma is present below the epidermis in the ridges in young stem but at maturity there develops sclerenchyma.
6. Parenchyma is present below the sclerenchyma or collenchyma in the ridges and directly below the epidermis in the grooves.
7. In old stem cortex consists of cork, cork cambium and cortex.
8. Endodermis is undistinguishable from cortical cells. The cells lack casparian strips.

Pericycle:
9. It is in sclerenchymatous patches.
Vascular system:
10. It phloem, secondary phloem, xylem and primary xylem.
11. Four longitudinal furrows of secondary phloem arc present which are wedged in between the secondary xylem cylinder.
12. Vascular bundles are conjoint, collateral, open and endarch.
13. Primary phloem is crushed and present in small patches.
14. Secondary phloem is in the form of a ring which remains intruded into the secondary xylem at four places.
15. Intruded furrows (four) of secondary phloem are arranged in the form of a cross.
16. In Bignonia unguis-catae, bars of sclerenchyma are present in the furrows of secondary phloem.
17. Cambium is single layered, present in between xylem and phloem and bent towards inner side along the furrows of secondary phloem.
18. Secondary xylem consists of vessels, tracheids, fibres and xylem parenchyma.
19. Due to the intrusion of the phloem at four places, secondary xylem is ridged and furrowed at four places.
20. Primary xylem is present close to the pith facing its protoxylem towards the centre. Its location is just opposite to the patches of primary phloem.
Pith:
21. It is thin walled and parenchymatous.
Secondary Growth:
Formation of four furrows of secondary phloem in the secondary xylem is due to the abnormal functioning of cambium which was behaving normally sometimes earlier.
At four or more places cambium produces less amount of secondary xylem towards inter side and large amount of secondary phloem towards outer side. Thus four wedges of secondary phloem are formed. They intrude into the secondary xylem and so xylem cylinder appears ridged and furrowed.
Identification:
(a) 1. Presence of vessels in the xylem. (Angiosperms)
(b) 1. Multicellular epidermal hairs.
2. Conjoint, collateral, open and endarch vascular bundles. (Stem)
(c) 1. Vascular bundles in a ring.
2. Presence of cambium. (Dicotyledones)
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