A Potpourri uses ToxicBurst on the party.
ToxicBurst (毒自爆 , Doku jibaku, lit. Poison Suicide?) is a Green Enemy Tech used by Potpourris in Chrono Cross. When Serge investigates Hydra Marshes in search of Hydra Humour to revive a poisoned Kid, he encounters several Potpourri. These stationary plants eject a virulent fume when their Hit Points reach a critical low, potentially causing the status effect Poison on party members and causing them to suffer low portions of damage.
The Potpourri in question will vibrate slightly before expanding to twice its normal size. A cloud of green-colored fumes will exit the tip of the Potpourri, which quickly surround all its foes.
To fend off predators, several plants release bursts of toxic fumes. This tech likely mirrors this natural defense mechanism.