Silver tree (The Sensorites)
The Doctor and Susan's homeplanet, Gallifrey, had bright silver trees, (TV: "A Desperate Venture", Gridlock, PROSE: The Sensorites, Cold Fusion, et al.) by one account literally named silvertrees (PROSE: The Infinity Doctors) and by another called Ulanda. (PROSE: Blind Fury)
Susan once told a Sensorite about her planet's silver trees. (TV: "A Desperate Venture", PROSE: The Sensorites) By one account, the specific trees Susan remembered were those in the House of Blyledge's walled garden, (PROSE: Cold Fusion) by another these trees were in a garden in Arcadia. (AUDIO: The Shoreditch Intervention)
The House of Lungbarrow was surrounded by a forest of silver trees which swayed in the wind. (PROSE: Lungbarrow)
The Tenth Doctor once recalled that the silver trees reflected morning sunlight, making it look like the forests were on fire. (TV: Gridlock)