Transpiration pulls water up through a plant as it evaporates from tiny pores in the leaves.

The longer version

Water leaving a leaf through tiny pores creates a pulling force that reaches all the way down the stem. Molecules of water cling to each other, so as one evaporates it draws the next along, and the whole column moves upward in a continuous chain.

The plant controls the loss by opening and closing the pores, which sit mostly on the underside of leaves. Closing them conserves water but also slows carbon dioxide intake, so there is a constant trade-off. Hot, dry, or windy conditions increase the pull and can outpace what the roots supply.

Where this entry sits

Plants and Trees gathers ordinary and surprising details about how green things live, from the tallest forest giants down to the moss on a garden wall. Expect notes on flowers, seeds, roots, leaves, fungi, and the quiet tricks plants use to spread and survive. The full list sits on the Plants and Trees page, where every entry is listed in order.