Trees of Light brings together the Swedish bassist Anders Jormin, the singer and fiddler Lena Willemark and the Japanese koto player Karin Nakagawa. Most of its twelve pieces are built on poems sung by Willemark in her native Älvdalen dialect. The stark, archaic sound of the 25-string koto, Jormin's muscular bass and her voice meet in a music rooted in Swedish folk song and Japanese classical tradition, yet open to free improvising.

The trio was Jormin's idea. He invited Nakagawa, a leading player of the 25-string koto who began studying with Keiko Nosaka at twelve and also works in Japan as a theatre actor and painter. According to ECM the three spent almost two years shaping the music, playing in Sweden and Japan. Nakagawa taught the others about the koto, Willemark taught her the Swedish polska, and Jormin set the frame for improvising and composing. The album was recorded in May 2013 at Konstepidemin in Göteborg, with Johannes Lundberg as engineer and Manfred Eicher as executive producer. It was Nakagawa's ECM debut, and Willemark's first record for the label since Jormin's In Winds, In Light in 2004.

The opening Krippainggler (If You Listen) starts with a long koto introduction, its chords struck with real force, before voice and bass enter. Jormin's instrumental Hirajoshi takes its name and material from the Japanese hirajōshi scale, with percussive koto accents set against viola and arco bass. Jag står kvar grows from bass and voice alone into an intense trio passage once the koto comes in. Elsewhere Willemark sings Minni unaccompanied, and the album's title comes from the poem Lyöstraini.

John Watson of Jazz Camera heard three cultures meeting and described "a recording full of mystery, unexpected twists, and powerful musical focus". In Stereophile, Richard Lehnert heard Bach-like counterpoint in Jormin's bass and called the sound "intimate, spacious, austere, rich". Jormin has long been the bassist of the Bobo Stenson Trio and has recorded for ECM with Don Cherry, Charles Lloyd and Tomasz Stanko. Willemark is a central figure of Swedish folk music, and had earlier led or co-led Nordan and Agram on the label.

This is the CD edition, ECM 2406, first released on 6 March 2015. The booklet prints the poems with English translations by Cynthia Zetterqvist.