From the Super Mario Wiki
The Megasmilax is a minor boss in Super Mario RPG: Legend of the Seven Stars. It was planted in the pipe in Land's End that leads to Nimbus Land to prevent any intruder from interfering with Valentina's plans to dethrone the royal family. During their search for the sixth Star Piece, Mario and his party comes across the Megasmilax and defeat it, freeing access to Nimbus Land.
Megasmilax originally starts as a single Smilax. However, after it is defeated, a Shy Away appears and pours recycled water on the plant, causing two more Smilaxes to grow, and then three, and finally one large Megasmilax accompanied by two Smilaxes.
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