Monocot and dicot root cross sections differ primarily in the organization of their vascular tissue and the presence of a pith.
Key Differences Between Monocot and Dicot Root Cross Sections
The following table summarizes the main differences:
| Feature | Monocot Root | Dicot Root |
|---|---|---|
| Vascular Cylinder | Xylem and phloem arranged in a ring around a central pith | Xylem forms a star shape with phloem between the arms; no pith |
| Xylem | Many xylem poles (10 or more) | Fewer xylem arms (3-5) |
| Pith | Present in the center | Absent |
| Example | Corn ( Zea mays) | Bean (Phaseolus vulgaris) |
Detailed Explanation
Vascular Cylinder
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Monocot Roots: The vascular cylinder of a monocot root features xylem and phloem arranged in a ring-like structure surrounding a central pith. The pith is a region of parenchyma cells located in the center of the root.
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Dicot Roots: In dicot roots, the vascular cylinder consists of a solid core of xylem in the center, typically shaped like a star. Phloem is located in the spaces between the arms of the xylem star. Importantly, a pith is absent in dicot roots.
Xylem
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Monocot Roots: Monocot roots generally have numerous xylem poles (10 or more), contributing to their ring-like arrangement.
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Dicot Roots: Dicot roots have fewer xylem arms, usually ranging from three to five, which form the distinct star shape in the center.
Pith
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Monocot Roots: A well-defined pith is a characteristic feature of monocot roots. It consists of parenchyma cells that store food and water.
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Dicot Roots: Dicot roots lack a central pith; the xylem occupies the central region.
In summary, the absence of a pith and the star-shaped xylem arrangement are key distinguishing features of dicot roots compared to the ring-like arrangement and presence of a pith in monocot roots.
