— Item examination - Japanese
"It appears to be some sort of ordinary plant, but..."
— Item examination - unofficial translation
The Purple Plant (紫の草 murasaki no kusa ) is an item which was intended to appear in Resident Evil 0 during its GameCube stage of development but was removed in the final release. You can get it in the Biohazard 0 TRIAL EDITION with the help of cheat devices such as Action Replay MAX or GameShark; however, it is not usable anywhere and lacks a 3d model as well.
It is possible that this item was supposed to be used to create the Purple Chemical.