For too many groups under the amorphous jam-band banner, the idea of "knowing your roots" extends only as far as the intersection of Haight and Ashbury in the late '60s. Not so for Galactic, an instrumental funk band that has internalized both the deep roots and budding blossoms of its native New Orleans. On last year's vast and varied Ya-Ka-May, the band collaborated with Crescent City musicians both old and new, from soul legends such as Allen Toussaint and Irma Thomas to rising stars of the city's bounce scene, such as Big Freedia and Katey Red. The result is an immersive album that colors Galactic's restless grooves with the guest stars' idiosyncrasies. For this show, Galactic will be joined by several special guests, though none more revered than Mike Gordon, the shaggy-haired, sleepy-eyed Phish bassist.