Brap! There are few sounds as satisfying as the brassy belch of a baritone sax. Like The Thing’s Mats Gustafsson, Alex Harding treats his baritone as an extension of the rhythm section, anchoring the pieces with fat, stomping riffs. But he also uses it as a lead instrument, coaxing lyrical phrases and atavistic howls from its valves, around which the brilliant altoist Darius Jones ducks and weaves. Taking in bluesy free-bop, exotic Ethio-jazz, and avant-garde abstractions, Grass Roots remains remarkably cohesive, distinguished by its taught and muscular post-hip hop sound, and the group’s highly sensitive use of space.