Why do a plant's leaves feel cool?

[EnumaElish]

Plant leaves are cool to the touch. In fact, that's one way of verifying whether it's a real plant. Can anyone explain why living plants feel cool?

 

[turbo]

Plants evaporate water through their leaves and evaporative cooling keeps them a little cooler than room temperature.

 

[jim mcnamara]

Leaves have openings - stomates. When the stomates are open the plant loses water by evaporation to the atmosphere, as Turbo says. This has several important effects. One is to allow the leaf's metabolic machinery to operate at temperatures that would normally slow it down: air-condtioning.

It also moves water from the roots up the stem, along with minerals. The stomates also allow CO2 into the leaf for photosynthesis to build more plant tissues. Plants are a net sink for carbon dioxide.

 

[DaveC426913]

I would suggest that the primary reason that leaves feel cool is that, evaporation aside, they are full of water, which is an excellent heat sink.