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| Anatomy of a Typical Dicot Root |
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| Example: Sunflower |
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| A transverse section passing through the root of Sunflower reveals the following details. |
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| Epiblema |
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| Epiblema is the outermost covering of the root formed by single layer of compactly arranged, barrel-shaped, parenchyma cells. The cells are characteristically thin-walled since they are involved in absorption of water. A cuticle and stomata are absent. Some of the epiblema cells are produced into long unicellular projections called root hairs. Hence, the epiblema is also known as piliferous layer. |
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| T.S. of a Dicot Root |
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| Cross-Section of a Dicot Root |
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| Cortex |
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| Cortex is a major component of the ground tissue of root. It is represented by several layers of loosely arranged parenchyma cells. Intercellular spaces are prominent. The cortex is mainly meant for storage of water. The cells also allow a free movement of water into the xylem vessels. |
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| Endodermis |
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| It is the innermost layer of cortex formed by compactly arranged barrel-shaped cells. Some of the cells in the endodermis are thin-walled and are known as passage cells. The passage cells allow water to pass into the xylem vessels. The remaining cells in the endodermis are characterised by the presence of thickening on their radial walls. These thickenings are known as casparian thickenings. They are formed by the deposition of a waxy substance called suberin. The casperian thickenings play an important role in creating and maintaining a physical force called root pressure. |
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| Stele |
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| Stele consists of pericycle, conjunctive tissue and vascular bundles. |
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| Pericycle |
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| Pericycle is a region that lies immediately below the endodermis. It is represented by a single layer of parenchyma cells. |
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| Conjunctive Tissue |
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| Conjunctive tissue is represented by a group of radially arranged parenchyma cells found in between the vascular bundles. The cells are specialised for storage of water. |
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| Vascular Bundles |
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| Vascular bundles are described as radial and tetrarch. There are four bundles each of xylem and phloem occurring alternately. Xylem is described as exarch. |
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| Pith |
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| Pith is absent in the older root. |
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