What relationship exists between humidity and number of stomata?
For the occurrence of photosynthesis, water should continuously flow through the plant organism. It means that the rate of transpiration, which takes place through the stomata, should be high. With increase in humidity, the rate of transpiration decreases, because water concentration gradient becomes lower. Thus, the number of stomata should increase with increase in humidity to ensure higher rate of transpiration. In turn, when humidity decreases, water loss becomes more likely. The plant has to conserve water, and thus, the number of stomata should be lower. Generally, there is an increase in the number of stomata with increase in humidity.