植物体内的水分 ,以水蒸气的形式通过叶的气孔散失到大气中 ,这就是蒸腾作用 ,这一过程可用下列实验验证。在阳光充足的正午 ,选一枝叶茂盛的树 ,用一透明白色食品袋套住一簇枝叶 ,将袋口拢紧 ,约 1ｈ后 ,在塑料食品袋上有大量水珠产生。这是因为从叶的气孔逸出的蒸气 ,遇冷变 The water in the plant body is lost to the atmosphere through the stomata of the leaf in the form of water vapor. This is the transpiration effect. This process can be verified by the following experiments. At the sunny noon, choose a leafy tree and use a transparent white food bag to cover a cluster of leaves and leaves the bag tightly. After about 1 hour, there are a lot of water droplets on the plastic food bag. This is because the vapor that escapes from the pores of the leaves is cold