Tangerine Tree was a fan project operating from 2002 through 2006 with the goal of collecting, preserving and distributing unreleased concerts and other audio material by the band Tangerine Dream. The creators of the Tangerine Tree project received permission from Tangerine Dream to release the collection on a strict non-profit basis. Several of the Tangerine Tree volumes have been used as the basis for official Tangerine Dream releases. The project collected just under 300 hours of material (291:39:26).
Material was collected from audience recordings, soundboard recordings, recordings of radio and TV transmissions and in some cases the purchase of studio masters. Only recordings of a high quality and a unique nature were considered for the core Tangerine Tree volumes. These recordings were professionally re-mastered and released on CD-R and accompanied by high quality artwork for the CD labels and case liners.
Tangerine Leaves releases were based on material that did not meet the quality standards of the Tangerine Tree or from concerts that were not considered notable among a series of concerts. If a better source was found, a Tangerine Leaves volume might have been deprecated and replaced by a Tangerine Tree volume. Starting from 1980, the music played during each of the shows in a single Tangerine Dream concert tour were very similar, so it was impractical to release many volumes of the Tangerine Tree with similar content.
Audio DVD Tree volumes consisted of about two sets of the Tangerine Tree volumes on a DVD that played to a slideshow of the CD artwork. These releases were standard DVDs with a menu structure and were available in both PAL and NTSC versions.