Why are spore bags at the underside of a leaf?

Spore bags, or sporangia, are typically located on the underside of a leaf to protect them from environmental factors such as direct sunlight and moisture loss, which can be detrimental to spore viability. This positioning also helps reduce the risk of predation by herbivores and allows for better dispersal of spores with the wind. Additionally, the underside of leaves often has a more humid microclimate, promoting spore development and release.