Here's how it works:
* Cohesion: Water molecules are attracted to each other (they "stick together") due to hydrogen bonds.
* Adhesion: Water molecules are also attracted to other polar molecules, like the cellulose in plant cell walls.
* Narrow Tubes: The tiny tubes (xylem) within the plant stem and roots are very narrow.
These factors combine to create capillary action:
1. Adhesion: Water molecules adhere to the walls of the xylem tubes.
2. Cohesion: The water molecules sticking to the walls pull up the water molecules behind them.
3. Surface Tension: This force creates a meniscus (curved surface) at the top of the water column, which further draws the water upward.
The combined forces of cohesion, adhesion, and surface tension, working within the narrow xylem tubes, allow water to move against gravity from the roots all the way to the leaves.
