Explain how plants meet the challenges of growing in hot, dry climates

In hot and dry climates plants will have an increased rate of transpiration, the release of water through the stomata of plant cells. In dry conditions there is a lack of water and as such, plants need to try to reduce this loss of water. For example, broad flattened leaves are made smaller to reduce the surface area to lose water from and may even be reduced to spines as seen in cacti. Adaptations to the stomata may also occur e.g. sunken into pits surrounded by hairs to increase the local humidity therefore reducing the diffusion gradient for the water to move out of the plant. The shape of the plant itself is also maximised to reduce water loss by reducing the surface area to volume ratio so there is a decreased rate of diffusion of water vapour out of the stomata. Cacti also contain tubers which contain water and allow the plant to survive for long periods of time with very little or no rainfall.