TOS s2e6 “The Doomsday Machine” and VOY s5e14 “Bliss”

Telepathic Pitcher Plant

The telepathic pitcher plant was approximately two thousand kilometers wide, and contained large amounts of bioplasmic energy.

Planet Killer

So, the giant cone is slightly larger in overall length than just the width of the “face” on the giant ship devouring mouth.

BananaVoyager for scale: