How leaves pull water upward

See how transpiration, stomata, cohesion, and xylem connect evaporation at a leaf to water movement through a plant.

Reviewed 2026-08-10 · 5 minute read

Original AI-assisted illustration commissioned for SciLens; no third-party source image used.

Core principle

Evaporation from moist cell surfaces inside a leaf and diffusion of water vapor through stomata create tension in the plant's water-conducting xylem. Cohesion between water molecules helps that tension pull a continuous water column upward.

A branching network of veins spreads from the central vein into smaller parts of the leaf.
The leaf looks hydrated and structurally supported rather than wilted.
Surface droplets are visible, but droplets alone do not prove transpiration because they could come from mist, rain, or condensation.

Roots absorb water from the soil, and the water enters xylem, the tissue that conducts water and dissolved minerals upward.
Inside a leaf, water evaporates from moist cell surfaces into air spaces. Water vapor then diffuses out through microscopic pores called stomata.
That water loss lowers pressure in the leaf xylem. Because water molecules cohere to one another and adhere to xylem walls, the tension can be transmitted down the continuous water column.
Water is pulled upward to replace what was lost. Guard cells adjust stomatal openings, balancing carbon-dioxide intake for photosynthesis against water conservation.

The image is a generated teaching illustration; stomata and xylem flow are too small or internal to see here.
Visible droplets sit on the outer surface and are not direct evidence of vapor leaving through stomata.

Reviewed by SciLens source review on 2026-08-10. Suggest a correction.