The ch'hala tree was a beautiful plant found on Cularin, and was an important part of the religion of the native Tarasin, though they claimed that the trees were not native to Cularin. Harvesting the wood was forbidden by the Cularin Compact of 154 BBY; only trees that died naturally were allowed to be cut down. The roots were crushed to make a fragrant tea. It was found in many Republic gardens on Coruscant, and notably being one of Supreme Chancellor Palpatine's favorite specimens. The tree's bark consisted of a pigmentation that was sensitive to pressure, including sound waves, so the tree would often change in color and pattern in response to noise.
In 31 BBY, the Metatheran Cartel secretly cut down several ch'hala trees in Cularin, using Caarite workers. The recently-born Cularin resistance discovered the fact, but did not tell their Tarasin allies because the Tarasin would begin a fanatic bloodshed against the Cartel, and the resistance hoped to avoid that violence.
Palpatine awarded Jedi Master Shaak Ti a grove of ch'hala trees, in recognition of honorable deeds done in protection of the Galactic Republic. Shaak Ti donated the grove to the Jedi Temple, where it was set up in a prominent location for all Jedi to appreciate.
The trees on Cularin were in fact all just one tree and were all interconnected underneath the soil. In 19 BBY, Wyrd attempted to turn the tree to the dark side of the Force and so allow them to control the Cularin ecology. However they failed in their attempt to do this.
These trees, planted all over Coruscant, became an integral component of a sophisticated spy system—codenamed Delta Source—that Palpatine used to monitor his courtiers and officers.
Many years later Grand Admiral Thrawn used this same system of trees to gather vital information about the workings of the New Republic Senate, which included key information on upcoming military campaigns.
It was found that the taproots of the trees hid a tube with sampling leads branching out of them. Pressure on the trunk of the tree, such as pressure from sound waves or the touch of a stray hand, would set off chemical changes in the bark. The chemical data was interpreted into speech patterns in a module on the taproot, while another module transmitted the data. The system was organic, so it could not be picked up by most sensor sweeps. It was this that prevented Delta Source from being found for so long.
The trees were uprooted after the incident.
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