Megasmilax

From the Super Mario Wiki

The Megasmilax, along with three Smilaxes.

Megasmilax's in-game appearance.

The Megasmilax is a giant Piranha Plant that lives in Bean Valley and wields impressive fire magic. The plant was created by Shy Away, one of Valentina's minions, to prevent outsiders from entering Nimbus Land and interfering with Valentina's plans to dethrone the royal family. Thus Shy Away planted Megasmilax in the pipe that led to Nimbus Land, blocking any intruders.

Megasmilax originally started out as one smaller Smilax. However, after Mario and company defeat this sole Piranha Plant, Shy Away appears and pours nutrients on the plant, causing two more Smilaxes to grow from the plant. These two are defeated as well, but Shy Away returns and grows three more Smilaxes in their place. Eventually, Shy Away creates one huge Megasmilax and two smaller Smilaxes to do battle with Mario's party. However, this was not enough to stop Mario. Ultimately, Mario and his allies overcome to numerous stages of Megasmilax and proceed to the entrance of Nimbus Land.

Megasmilax bears a strong resemblance to the Naval Piranha and Lava Piranha.