This is a trope, mainly in science fiction, where a ship or vessel of some kind is literally made out of a tree. Not merely made out of wood, or that a tree was used in the construction, this ship actually looks like (and possibly functions as) a giant tree. A key element is that the tree should be living, and was grown/created/transplanted specifically for the purpose.
Most often used in Science Fiction, though not necessarily limited to it. In certain cases it may be used to show a race as basically Space Elves who have both high technology and still are in tune with nature.
Anime and Manga
- Juraian ships in Tenchi Muyo! are all sentient, giant trees that are shaped to look and function like spaceships. This also means that after being shot down, they can be regrown as long as the core tree survived.
- The Makaiju ("Doom Tree" in the American dub) from Sailor Moon — originally a tree on an alien planet, when the planet was destroyed it uprooted itself and proceeded to travel through space, sheltering some of the inhabitants of the planet in its roots.
- The rocketship in Saga. Apparently there's an entire forest of rocketship trees, and they don't die once they've blasted off. They're very much alive as they travel through space, and seemingly fond of their passengers.
- The Fountain: The Tree of Life in the "space traveler" sections of the film.
- In the Hyperion Cantos, the Ouster "Treeships", which are built around a single, massive living tree made vacuum-sealed and spaceworthy by containment fields.
- In Raft by Stephen Baxter, one of the strange lifeforms in the high-gravity universe is a species of mobile floating trees. Humans turn them into vessels and steer them through space.
- Alastair Reynolds has a version of this in his Revelation Space Series. The "Greenfly" infestation that is depicted taking over the galaxy in Absolution Gap is shown to be billions of self-contained biospheres containing trees and tree-like plants.
- The Last Continent does this with a tree that's been made into a boat by the local god of evolution. The sail is a leaf, the hull is a floating seed, etc.
- Animorphs: Pemalite ships use huge trees as computers for their spaceships. Even Ax (whose species' ships have giant biodomes filled with forests and plains) finds it ridiculous.
- Space vessels created by elves in the Dungeons & Dragons Spelljammer setting are grown, not built, from living, leafy trees.
- Orion's Arm has what are called "Dyson Trees". They're genetically engineered giant plants that can survive in vacuum and synthesizes nutrients from ices found in a comets or icy asteroids, into which they're rooted, and can grow into vast orbital habitats. Inside their trunks and larger branches there are sealed hollows filled with air, inside which other lifeforms — like humans — can live, while their spherical canopies support further air- and water-filled habitats, as well as space-adapted lifeforms.