Cheem

Cheem, also referred to as Tree of Cheem, are intelligent humanoid trees who descended from the rain forests of Earth.

In Worlds in Time
The NPC assistants Silas and Talia in Worlds in Time are Cheem. Another Cheem NPC, Arute, plays a significant role in the Mars interventions.

In Doctor Who
The Cheem first appeared in the episode The End of the World (2005). The Forest of Cheem sent representatives to witness the destruction of Earth from Platform One, where they met the Ninth Doctor and Rose.