Linked from
The 26 pages that link to Stomata, each with the reason it gives.
EvapotranspirationBroader topic: Their opening and closing regulate much of plant transpiration.
PlantBroader topic: Their opening balances carbon dioxide uptake against water conservation.
TerrestrializationBroader topic: Stomata let land plants exchange gases while limiting dehydration.
Plant structuresBroader topic: These leaf pores regulate gas exchange and water loss.