New research has shed light on when plants first evolved the ability to respond to changing humidity in the air around them, and was probably a feature of a common ancestor of both flowering plants and ferns.
Key to the regulation mechanism are tiny holes, or pores, on the surface of leaves, called stomata. These enable the plant to regulate the uptake of CO2 gas as fuel for photosynthesis, and the loss of water vapour – a constant balancing act that requires the pores to open and close according to changing conditions. This ability is important to agriculture because it helps crops to use less water to grow.
Plants first evolved stomata soon after they moved from water to land, some 450 million years ago, but scientists are still uncertain about the evolutionary pathway they took and the point at which plants became able to choose whether to open or close the pores in response to their environment.
Read more at: University of Birmingham