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The below mentioned article provides an Anatomy of Phylloclade and Phyllode. After reading this article you will learn about: 1. Ruscus-Phylloclade 2. Acacia Moniliformis-Phyllode (Common Name: Australian Acacia).
Ruscus-Phylloclade:
(Phylloclade is a modified stem which appears and functions like a leaf)
T.S. appears flat, leaf-like and reveals following tissues:
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Epidermis:
1. A single epidermal layer is present on upper as well as lower surfaces representing upper epidermis and lower epidermis.
2 A thick cuticle is present on the outer wall of the cells of both the epidermal layers.
3. Epidermal cells are radially elongated and their continuity is broken by many stomata present on both surfaces.
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4. Stomata consist of guard cells filled with chloroplasts and clear sub-stomatal chamber.
5. Central region of the material is somewhat bulged.
Chlorenchyma:
6. Immediately below the upper epidermis are present one or two layers of loosely arranged parenchymatous cells filled with chloroplasts.
7. The cells are rounded or oval is shape and leave many intercellular spaces.
Parenchyma:
8. Parenchymatous region is well- developed and present next to the chlorenchyma.
9. The cells are thin-walled, loosely arranged and leave many intercellular spaces.
Vascular System:
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10. Many vascular bundles are arranged in parallel series.
11. In the central bulged region of the section are aggregated few amphivasal vascular bundles surrounded by a bundle sheath.
12. A thick, sclerenchymatous bundle sheath is present around each vascular bundle.
13. Each vascular bundle is concentric and amphivasal (phloem in the centre surrounded by the xylem).
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14. Well-developed, parenchyma is present in the central region.
Leafy Characters:
1. Dorsiventral symmetry.
2. Presence of upper and lower epidermal layers with stomata.
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3. Central bulged region is comparable with midrib.
4. Presence of chlorenchyma below upper epidermis.
Stem-like Characters:
1. Presence of amphivasal vascular bundles.
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2 Phloem does not face towards the lower epidermal layer.
3. Parenchyma of the central bulged region is comparable with the ground tissue or pith of stem.
4. Well-differentiated cortex.
Xerophytic Characters:
1. Presence of thick cuticle.
2 Sclerenchymatous bundle sheath.
Acacia Moniliformis-Phyllode (Common Name: Australian Acacia):
(In phyllode, the lamina of the leaves is reduced, and from the remaining part, i.e., petiole, a flat, leaf-like photosynthetic organ is developed. So it is a modification of petiole.)
T.S. of the meterial is flat, appears leaf-like and reveals following tissues:
Epidermis:
1. A single row of epidermal cells is present on upper as well as lower surfaces.
2. Outer wall of the epidermal cells is thickly cuticularized.
3. Epidermis is interrupted by many sunken stomata, each with a clear sub-stomatal chamber.
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4. Cells of the epidermis are rectangular in shape but two extreme ends of the section possess radially elongated cells.
Palisade:
5. Just below the epidermis are present few layers of palisade.
6. Palisade cells are radially elongated and filled with many chloroplasts.
7. Many intercellular spaces are also present in the region.
Parenchyma:
8. Next to the palisade is the parenchyma region which is well-developed and central in position.
9. The region consists of thin-walled, rounded cells with many intercellular spaces.
Vascular Tissue:
10. Vascular bundles are many and arranged below the palisade.
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11. There are two big vascular bundles in the centre facing their xylem to each other. One big vascular bundle is present at each corner. Many smaller vascular bundles are present inner to the palisade.
12. Central and corner vascular bundles are bigger in size and remain surrounded by well-developed sclerenchyma.
13. Smaller vascular bundles are surrounded by a layer of thin-walled cells.
14. Vascular bundles are composed of xylem and phloem.
15. Xylem in each vascular bundle faces towards the centre and consists of tracheids, vessels and xylem parenchyma.
16. Phloem consists of sieve tubes, companion cells and phloem parenchyma. It faces towards the outer side or epidermis.
Xerophytic Characters:
(a) Thick cuticle and radially elongated epidermal cells.
(b) Sunken stomata.
(c) Well-developed sclerenchyma.
Leafy Character:
(a) Palisade tissue is present.
Petiole Characters:
(a) Vascular bundles in a ring.
(b) Central and corner bundles are large in size.
