Horsetail

Horsetail plants, along with |Brick, are what the original manual for Super Mario Bros said Bowser turned the citizens of the Mushroom Kingdon into. Horsetails are items found in an area of Petal Meadows in Paper Mario: The Thousand-Year Door. Just before reaching the area with the bridge, coming from the Rogueport pipe, there is a Candy Cane that, when hit with a hammer, sinks down and bounces back up. After hitting the cane 10 times, a horsetail comes out. This can be done several times, after exiting and re-entering the area. They heal 3 HP.

Horsetails are also in Super Paper Mario, where they restore 7 HP and cures poison, and are usually dropped by Putrid Piranhas. They could also be bought in the Itty Bits in The Dotwood Tree for 18 coins.