Improvisation is synonymous with jazz. It’s the aspect of the genre that makes it romantic, spiritual, dangerous. But a jazz song doesn’t keep my attention without the pre-planned parts. Especially the head – the composed section that begins the tune and provides the base color for the soloists to brush over. This small amount of structure bears a disproportionate amount of responsibility for a song’s success. And it’s where the new Portland quartet Native Isles truly excels. Led by trumpet player and scene mainstay Emma Stanley (currently a member of The Fogcutters, OC and the Offbeats, and Akela Moon), Native Isles occupies that groove-based common ground that artists like Charlie Hunter and John Medeski rode to success in the ’90s, incorporating just enough rock and funk elements to poach fans from both the jazz and jam-band sets. On her group’s self-titled debut EP, Stanley gets her first chance to present her vision as a bandleader on record. And from the opening notes of “One In Seven,” she makes the most of it. Leading the group through an acrobatic head that chops up a minor scale into something fascinating, and vibrant, and entirely new, Stanley sets up the ensuing solos beautifully. Her tone is warm and fluid throughout, her instrument the clear touchpoint, a sign that everything’s under control. Guitarist Pete Morse is the other dominant voice, transforming “Terri the Turtle” into a loud, spacey ride. But Native Isles reaches its greatest heights when Stanley has the reins. “Teeny Weeny” boasts a hook so casually funky, it feels like it’s always been around. And the closing “Casual Allie” strolls confidently into frame with a vamp lifted from Edie Brickell’s evergreen jam “What I Am.” When Stanley, Morse and keyboardist Tyler Stanley lock into the ice-blue cool of the melody, you’ll feel like you’re strutting even if you’re stuck in State Street traffic.