Water absorbed by plant rhizomes moves from root to stem. Water travels from the stem to the branches and leaves through transport tissue. Water reaches palisade parenchyma and spongy parenchyma cells through leaf veins. Due to the heat and pressure of the leaves, the water turns into vapor and accumulates in the intercellular spaces and stomatal chambers. When the stomata open, the vapors are released into the atmosphere by the process of transpiration. Diffusion processes are accelerated when air humidity is low and the rate of transmission increases. The stomata of plants are open during the day and respiration takes place. The stomata are fully open from 10-11 am and 2-3 pm. Other times are partially open. The stomata of plants like orchids, cactus, pineapple etc. are open at night.