Is “Joint Happening” a fusion record? Its billing certainly promises one. San Francisco’s Mushroom makes music to stare at lava lamps by—lush, progressive psychedelia with stoners’ grooves—and trumpeter Eddie Gale is an undervalued master of avant soul-jazz. But the disc at first sounds like a straight-ahead acid-rock jam: dense and lysergic. Pat Thomas’ drums and Ned Doherty’s Jack Brucenish bass set the pace with Gale’s horn the leader among many instruments (including guitar, Rhodes, Mellotron, vibes, and flute) that provide sumptuous colors. Only the darkly (P-)funky “Our Love,” the sixth of seven tracks, suggests jazz fusion. Listen closer, though. Every measure Gale plays, whether on the seductive “I Don’t Need to Fight, to Prove I’m Right—I Don’t Need to Be Forgiven” (titles cribbed from classic-rock lyrics are a Mushroom trademark) or the eerie atmospheres of “Selling Oakland by the Pound,” has a solid jazz aesthetic. He constructs his solos with blue notes and dissonances, half-steps and huge intervals, Parker-esque bebop lines and Armstrong-ian gutbucket phrases. And he does it without breaking from Mushroom’s psychedelic festivities. His languid tone is perfect on the tranquil “Peace,” floating through and around the membranes of guitar and flute-voiced Mellotron, and it’s Gale who puts the freakiness into the album’s closer, “The Spirit,” which is just a rhythm exercise without his winding melodies and shrieks. Already delicious ear candy on its surface, such hidden depths make “Joint Happening” intriguing—it’s not fusion so much as evidence of the common ground between acid rock and New Thing jazz. Nowhere is that overlap more apparent than in the disc’s centerpiece, “I Was Torn Down at the Dance Place, Shaved Head at the Organ,” an 18-minute drama of tribal percussion, Erik Pearson’s flute, and Gale’s urgent, prodding trumpet. Piano, cymbals, and other instruments slowly enter the mix, building to whirling-dervish intensity. It could have been recorded by Can (for whom Mushroom expresses admiration), Sun Ra’s Arkestra (of which Gale was a member), or both together. In that light, the collaboration doesn’t fulfill typical expectations, which would have had each performer adapting his style to accommodate the other. Instead, “Joint Happening” works because Gale and Mushroom were so compatible from the start. It’s an unusual but insightful approach—and, given how many fusion acts tried assimilating the two styles and got lost in a sea of wankery, perhaps the correct one.