It's a testament to the strange alchemy that comes out of Medeski Martin and Wood's performances that an indefinable, improvisation-driven keyboard trio can draw a large, thoroughly rapt crowd to UCLA's stately Royce Hall on a Friday night.

Now in their second decade since coming together in 1992, the trio has trafficked in a unique, groove-oriented mix drawing from elements of hip-hop, African music, funk and avant-leaning noise into a sound they would happily admit is far from a purist's definition of jazz. But the spirit of that tradition (its members have studied or performed with the likes of Geri Allen, Dave Holland and Bill Frisell) is never out of sight, no matter how far out the group roams.

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The trio rode a brief (and inadvertant) association with Phish and the jam-band circuit to Blue Note Records  in the '90s and developed a comparatively high profile for an organ trio over its career. Dipping into various markers along the group's catalog, Friday's show presented by Center for the Art of Performance at UCLA had the feeling of a summation of Medeski Martin and Wood's strengths.

Nodding as much to the group's debut "Notes from the Underground" as its 2012 live release "Free Magic," the opening (mostly) acoustic set threatened to steal the show, even as John Medeski's fireworks on organ, Clavinet and Mellotron have become something of the band's signature over the years. In a loose, restless set, the trio shifted seamlessly from song to song, furiously exploring the outer edges of an ever-accelerating melody here, a smoky, shape-shifting take on barroom-ready blues there.

Even without his usual arsenal, Medeski remained the group's focal point as each song gathered and receded. (The pianist's boundless invention recently revealed yet another facet with "A Different Time," a surprisingly delicate and contemplative solo album for the relaunched Okeh Records.)

"Doppler" from "Free Magic" seemed to swirl in a variety of directions atop a percolating shuffle from drummer Billy Martin before coming back to its flickering piano lead. At one point Medeski left the piano for a seven-foot-tall, bassoon-like Slovakian shepherd horn that unfurled gruff flute-like melodies as the group captured a spooky, alternate-world music framed by metal percussion that conjured a gathering storm with a mix of breath, bells and bass.

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Returning for a plugged-in second set, the group looked back on some of its most challenging yet rewarding material. "Big Time" from 2000's "The Dropper" set the night's tone with Medeski's organ chewing into a deep funk groove from his rhythm section, and "Bone Digger" slinked out from a warped keyboard glide from Medeski into a fuzz guitar melody from Wood's Hofner bass.

A slower, smokier turn from the album "Combustication" pointed to the group's abilities to craft a sticky melody, and "Fèlic" was a stormy, free-jazz workout that culminated in a thrashing finish from Martin on the drums that stopped on a dime with a single cymbal crash. Throughout, parts of the crowd howled with every soloist's venture and every return to the top, and even shared some laughs as one of Martin's percussion quests found him tapping shakers, chimes and a few bird calls.

The night closed on a more contemplative note with "Mo Ti Mo," an exploded cover of King Sunny Ade that began with shakers and a beautiful, starlit keyboard melody. As the song gracefully settled, Medeski stepped to the edge of the stage with a Melodica and continued the song's arc backed by only rattling, woodsy sound of shakers and acoustic bass. The crowd fell church quiet as the song became something almost jarringly intimate, making the prospect of the next 20 years sound that much better.

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Twitter: @chrisbarton