Dragonsbane is a flower species that arrived and bloomed throughout the Dragon's invasion of Earth. It has made most environments uninhabitable due to its toxic nature to humans and has mutated other living creatures on Earth into hostile creatures. The sickness that humans catch from it is called Dragon Sickness.
In 7th Dragon, walking on Dragonsbane will damage the health of player's party members. Starting from 7th Dragon 2020 and onward, Dragonsbane no longer have any effect on the player's gameplay except as plot element and occasional obstacles that block off the players' path to certain areas.