Regalis V

The Plantworld is some planet in the Beast Machines portion of the Generation 1 continuity family.

Somewhere in space, far away from Cybertron, lies a planet with little to no animal life, dominated by ambulatory plants. Botanica's ship landed there, and she and her crew took the forms of its native plants to blend in, avoid the attention of the carnivorous (herbivorous?) ones, and study them, similar to Optimus Primal's team on Earth. Home Soil

Nothing else is known about the planet, not even its name, so it is sometimes referred to by fans simply as the "Plantworld". Or those prone to witticisms might call it the "Planet of the Grapes"

From Teletraan I: The Transformers Wiki, a Wikia wiki.