The colossal wroshyr trees were native to the Wookiee homeworld of Kashyyyk. These trees were literally the cradle of Wookiee civilization, supporting large cities kilometers above the planet's forest floor. They were also present on Alaris Prime, with the Wookiees inventing various theories as to how the tree traveled there from Kashyyyk.
The massive trees dominated the landscape, with over 1,000 different varieties, that had adapted to everywhere except for the planet's poles. The trees could live up to 50,000 years, reaching kilometers in height. The trees were so big that entire communities could live within their hollowed-out trunks, which, like caves, provided both shelter from the elements and protection against the planet's many predators. In coastal environments, the wroshyrs did not grow as thickly together. The tropical wroshyrs of the Wawaatt Archipelago were much smaller than the forest giants, averaging 300–400 meters.
A single one of their wide branches could form a natural road, but they were also capable of melding together wherever they met, making even larger foundations for Wookiee cities. The melding together of two limbs of different trees was often used as a representation of the bonds of friendship and cooperation in Wookiee communities. In actuality, the merging of limbs of different trees may have indicated that the "trees" were actually part of one massive organism.
The wood of the trees could be harvested for many things such as water, food, building materials and wroshyr lice syrup, commonly used on top of Franjo Pancakes. Uninhabited trees were harvested for timber, both for domestic use and offworld export. The leaves and the bark were used in the manufacturing of textiles, weapons, furniture, utensils, and decorative objects, as well as vrortik. Many parts of the tree, especially its sap (known as "tree blood"), were used in medicines, foods, beverages, and rituals. Wroshyr sap and leaves could also be distilled to provide fuel, oil, and chemicals.
The Tree Carers Wookiees gathered and saved seeds from wroshyr cones to plant new trees.
The trees' abnormally large size was due to terraforming attempts by the Rakatan Infinite Empire years before the Galactic Republic. After the species' empire fell and all remaining Rakata were driven back to their home planet, the terraforming machines could not be shut down, resulting in the foliage growing to great sizes.
During the time of the Cold War, a proxy conflict between the Sith Empire and Galactic Republic, one of the oldest wroshyr trees on Kashyyyk—reportedly millennia old—was dying, and eventually someone was sent to examine its rings and learn through them the planet's history.
- Heir to the Empire Sourcebook
- Alliance Intelligence Reports
- Heroes & Rogues
- The Truce at Bakura Sourcebook
- The Thrawn Trilogy Sourcebook
- Star Wars: Complete Locations
- Secrets of Kashyyyk"—Star Wars Gamer 4 "
- Callsigns: Names of Kashyyyk"—Star Wars Gamer 10 "
- Ultimate Alien Anthology
- Star Wars: Empire at War: Forces of Corruption Expansion: Prima Official Game Guide
- Star Wars Fandex Deluxe Edition
- The Complete Star Wars Encyclopedia
- Star Wars: Edge of the Empire Core Rulebook
- Suns of Fortune
- Forged in Battle