Tree

A tree was a woody form of plant that grew on several planets. Generally forests were composed (at least partly) of trees. The forests of Eden were dense even in the small section captured by Tryst's Continuous Event Transmuter. (DW: Nightmare of Eden)

Vislor Turlough once described the trees on Trion as being three times the size of Earth trees, with plate-like thick mauve and purple leaves growing in spirals up blood-red trunks. (BFA: Loups-Garoux)

Calderon Beta was home to a four hundred foot tall tree "growing out of a clifftop on the north side of a mountain in the middle of the sea". (Night and the Doctor: First Night)

A species of tree existed on Gallifrey with silver leaves. These reflected the morning sunlight, making it look like the forests were on fire. (DW: The Sensorites, Gridlock) There were also green forests, similar to those on Earth.

Intelligent or sentient trees
Whilst on Earth in the 1820s the Rani mined a section of forest with mines that turned humans into trees. Following their transformation the former-humans retained some level of consciousness. (DW: The Mark of the Rani)

In the year 5345 The Doctor encountered a group of Androzani trees who were attempting to flee their doomed homeworld. (DW: The Doctor, the Widow and the Wardrobe)

By 5,000,000,000 many trees that had originated on Earth had achieved sentience and humanoid form. (DW: The End of the World)