Krista Kopper came to the attention of Plastic Sax while performing with touring musician Thollem McDonas at 9th & State in 2021. The bassist made some of the most valuable contributions amid a band of ringers. The peripatetic enterprises of drummer Evan Verploegh are covered extensively at Plastic Sax. Both musicians are core members of Kansas City’s Extemporaneous Music and Arts Society. Daringly intimate and relentlessly engaging, Kopper and Verploegh’s new duet album For the Trees affirms the boldness of the collaborators. “II” is among the selections in which the dual sets of sounds become indistinguishable from one another. “VII” might be a hit single in a realm that treasured free improvisation while “I” could be repurposed as the ominous opening strains of an avant-garde opera. Far from austere, “IX” is among the fun-loving tracks making For the Trees one of the most distinctive albums created by Kansas City musicians since Singles, Verploegh’s remarkable 2021 duo album with saxophonist Ben Baker.