Gothel gives a toadstool to Rapunzel as an opportunity to curse Cecelia's heart and drive her away from Marcus. Rapunzel, at first, rejects the idea of hurting an innocent person for her own gain, but as her jealousy grows after her daughter Drizella shows favoritism towards Cecelia, Rapunzel crushes the toadstool's liquid into the woman's drink. ("One Little Tear")
After Gothel's daughter, Alice, is imprisoned in the Tower, Gothel poisones her father, Hook, who has been living with her daughter, in order to punish him. ("Knightfall")
Years later, Drizella coats a knife with liquid from the toadstool in an attempt to poison Henry's heart but she fails after Cinderella arrives to save him. ("Pretty in Blue")
Ambrosia is an Underworld plant. It appears in the twentieth episode of the fifth season. Also known as the food of the gods, ambrosia is so powerful that they absorb all the magic around them. One of their magical properties is to allow their eater to escape the Underworld. They grow in a temple at a far down point of the Underworld. To access to the field, one test must be completed. Unbeknownst to everyone, Hades cut the tree of the Ambrosia, so the plant disappeared.
Boro Grove's Spore Flowers are Wonderland plants. They appear in the sixth episode of the spin-off series. The spore flowers grow on trunks of Boro Grove trees, and they exude a purple-pinkish cloud of fog that gives off a fragrant perfume. Those that inhale the scent are plagued with almost instant amnesia and are drawn into a lively stupor of wanting to stay in the Boro Grove. If the person stays in this state after a short period of time, he or she will begin turning into a Boro Grove tree. The spore flowers affect humans, except for those who don't have their hearts.
Grapevines are Wonderland plants. They appear in the eighth episode of the spin-off series. This plant has the ability to transmit sounds through its vines. When Cyrus is trapped in its vines, and while wrestling to untangle himself, the grapevine broadcasts his sounds of struggle miles away in the maze. Tweedledum hears Cyrus through the grapevine and prepares to report this to the Red Queen.