As part of Delta Source, the Ch'hala trees on Coruscant played a role. A species of tree called the ch'hala tree originated on the planet of Cularin.
A striking plant from Cularin, the ch'hala tree held religious significance for the native Tarasin, despite their belief that the trees didn't originate on Cularin. According to the Cularin Compact of 154 BBY, harvesting the wood was prohibited; only trees that had died naturally could be felled. Aromatic tea was made by crushing the roots. They thrived in numerous Republic gardens on Coruscant, and were a favorite of Supreme Chancellor Palpatine in particular. The tree's bark possessed a pigmentation that reacted to pressure, including sound waves, resulting in frequent color and pattern changes in response to noise.
In 31 BBY, the Metatheran Cartel secretly felled a number of ch'hala trees on Cularin, employing Caarite laborers. The newly formed Cularin resistance became aware of this, but refrained from informing their Tarasin allies, fearing a fanatical and violent response from the Tarasin against the Cartel.
To honor Jedi Master Shaak Ti for her commendable actions in safeguarding the Galactic Republic, Palpatine gifted her a grove of ch'hala trees. Shaak Ti then donated this grove to the Jedi Temple, where it was prominently displayed for all Jedi to enjoy.
Remarkably, the trees on Cularin were interconnected beneath the soil, forming a single organism. In 19 BBY, Wyrd made an unsuccessful attempt to corrupt the tree with the dark side of the Force, hoping to control the Cularin ecology.
During the era of the Galactic Empire, Palpatine strategically placed these trees throughout the Imperial Palace, especially within the Grand Corridor.
These trees, distributed across Coruscant, became a vital part of a sophisticated espionage network known as Delta Source, which Palpatine employed to monitor his officers and courtiers.
Years later, Grand Admiral Thrawn leveraged this same tree system to glean crucial insights into the operations of the New Republic Senate, including significant details about impending military operations.
It was discovered that the taproots of the trees concealed a tube with sampling leads extending from them. Pressure applied to the tree's trunk, such as from sound waves or a stray touch, triggered chemical reactions in the bark. This chemical data was converted into speech patterns by a module on the taproot, and another module transmitted the information. Due to its organic nature, the system evaded most sensor sweeps. This characteristic allowed Delta Source to remain undetected for an extended period.
Following this discovery, the trees were uprooted.