Yes, Plants do need Water

We all so diligently water our plants, but do they really want it? (Photo by James Woodin)

Transpiration

• well, yes
• plants do indeed want water
• and if you’re keeping a plant captive in your home, in a pot, you should probably water it
• but plants do get rid of much of the water they absorb
• only 0.5% of the water absorbed by plants is used for growth and metabolism
• I was surprised to learn this too
• the rest of the water is lost through a process called transpiration
• transpiration is the evaporation of water through stomata
• stomata are the tiny pores, usually found on the underside of leaves
• these pores are surrounded by guard and accessory cells that regulate when the stomata are open
• and they don’t just open to get rid of excess water
• they open to absorb carbon dioxide from the air to fuel photosynthesis
• the transpiration of water is simply the cost of absorbing the carbon dioxide

So our plant friends are not bothered by our watering them at all, nor are they perturbed by the rain. They simply must let go of much of the water they absorb for the sake of photosynthesis, the driving force of primary production. Every benefit has a cost.