Hmm... harry potter related....
How about... wait.. no.. hmmm. Uhh....
*brain brims with Harry Potter knowledge. Or maybe just air.*
ummmmmmmm I think...
Ahha! I can only remember 2 plant names, so...

How about:

1. Big one is the Womping Willow (or Creepy Cactus or Crashing cactus?... umm... never mind)
2. Medium one (larger of the smallish ones) could be Devil's Snare (or a nickname, like just Snare, dunno, something like that).
3. Small one could be Wormtail.

*brain melts from Harry Potter recollection*

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Ello, i can haz cheezeburgerz - me iz spekith engrish! - ok dis randum.