pressure bomb

plant

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July 13, 2026

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The term "pressure bomb" in botany refers to a device used to measure the tension, or negative pressure, within a plant's xylem. This tension is crucial for understanding how water moves upward in plants, especially in tall trees.

While root pressure, generated by osmotic pressure in root cells, can push fluids upward, it's insufficient to overcome gravity in tall plants. The primary force driving water movement is transpiration pull, where evaporation from leaves creates a tension that pulls water up through the xylem. The pressure bomb allows scientists to quantify this tension by applying external pressure to a cut stem until water emerges from the xylem, indicating the internal negative pressure.12

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angiosperm
Process of xylem transport
…ingeniously simple device called the pressure bomb. A small twig is inserted in a container (the pressure bomb), its cut stump emerging from a tightly sealed hole. As pressure is applied to the container and gradually increased, water from the xylem emerges from the cut end as soon as the…
Read More
…ingeniously simple device called the pressure bomb. A small twig is inserted in a container (the pressure bomb), its cut stump emerging from a tightly sealed hole. As pressure is applied to the container and gradually increased, water from the xylem emerges from the cut end as soon as the…
Read More