The festival is named after the hollyhock ("aoi") leaves used as decoration throughout the celebration as well as offerings to the gods. During the Heian Period, these leaves were once believed to protect against natural disasters such as earthquakes and thunder, and were often hung under the roofs of homes for protection. The plants used in the Aoi Matsuri may not be hollyhock, but possibly wild ginger. Although due to the rarity of these plants, other plants with similarly shaped leaves have been used in the festival instead, such as the leaves of the katsura tree.