We all know both Short and Tall Grass (+ Ferns) are replaceable via placing any other block over them. And if we replace Tall Grass or Tall Fern with any other tall plant which occupies two blocks, Tall Grass gets fully replaced without any issues... except for Pitcher Plant. For some reason, if you place Pitcher Plant over Tall Grass or Tall Fern, it will replace both parts of it as intended, but will also immediately break back into the item.