From the Super Mario Wiki
Smilax is a three-headed Piranha Plant found in Bean Valley in Super Mario RPG: Legend of the Seven Stars. With mineral water from a Shy Away, he grows from a single Piranha Plant head to two, then three, then two small ones and one large one, called Megasmilax. Smilax was most likely grown by Shy Away at Valentina's request to act as a guardian of the entrance to Nimbus Land, as part of her larger plan to take over the cloud kingdom. Smilax can be superficially compared to Petey Piranha as being a somewhat-personified Piranha Plant.
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