The cut end of herbs stem just above the ground cause loss of water.This is due to

Options

A. Physical force theories
B. Root pressure
C. Vapourisation of water
D. Non-osmotic absorption of water

Answer

**Step-by-Step Text Solution:**

1. **Understanding the Question**: The question asks why the cut end of a herbaceous stem, just above the ground, causes loss of water.

2. **Identifying the Phenomenon**: The phenomenon being described is known as "guttation," which is the loss of water in the form of droplets from the plant. This occurs from specific areas of the plant, including the cut end of the stem and the leaf margins.

3. **Role of Hydathodes**: The leaf margins have specialized structures called hydathodes, which are pores that facilitate the loss of water droplets. This is important to note as it relates to the overall process of water loss in plants.

4. **Cutting the Stem**: When a segment of the stem is cut, especially near the tip, water droplets may ooze out from the cut end. This is a direct observation of guttation.

5. **Understanding Root Pressure**: The primary reason for the water loss from the cut end of the stem is due to root pressure. Root pressure is the pressure exerted by the roots of the plant, which pushes water upward through the plant.

6. **Timing of Root Pressure**: Root pressure is typically highest during early morning and late evening when transpiration rates are lower due to the absence of sunlight. This allows for a significant buildup of pressure in the roots.

7. **Role in Transpiration**: While root pressure provides a moderate push of water, it is important to note that it is part of a larger process of transpiration and translocation, which involves a continuous chain of water molecules moving through the plant.

8. **Conclusion**: Therefore, the loss of water from the cut end of a herbaceous stem is primarily due to root pressure, making the correct answer to the question option 2.

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