The Smithsonian’s program for Jazz Appreciation Month is separate from D.C.’s local JAM calendar, which last night featured the Calvin Jones Big Band Festival – a triple billing of the Jazz Ensembles from Howard University, University of Maryland, and the University of the District of Columbia.

Which meant that the bulk of the Thad Wilson Jazz Orchestra was unavailable for the usual Monday night gig at Bohemian Caverns. Undeterred, Wilson and the remainder of his players (trombonist Steve Shaw and saxophonists John Kocur, Dustin Mollick, and Brian Settles) brought in a substitute rhythm section —- bassist Eric Wheeler and drummer David McDonald, with Wilson foregoing his usual trumpet for a battered Fender Rhodes —- and turned last night into an informal jam session. “Think of us as the official after party of the festival,” he said.

After party indeed, since throughout the night festival participants (whether members of Wilson’s band or no) filed into the club and onto the stage. Vocalist Chad Carter was a huge presence, sounding for all the world like bop-era singer Kenny Hagood on his version of “Body and Soul,” as was alto saxophonist Stan Cherednik —- who didn’t quite upstage fellow altoist Kocur, the TWJO’s star soloist, but held his own with a haughty lyricism. It was a loose, ragged, just-plain-fun affair for a very small but appreciative audience.

Well…mostly appreciative. In the second set, Wilson took the microphone and asked the crowd of 15-20 people, “How many of you think you know something about jazz?” Four or five hands shot up. “Well,” he continued, “What we’re about to do, I call jazz. Let’s see what you think.” Upon this, the group (which also included a trumpeter whose name even Wilson didn’t know) launched into a long improvised bit of avant-garde fusion. Whether everybody else called it jazz I don’t know — I certainly loved it — but I can attest that one previously enthusiastic spectator now had her fingers in her ears. Such is the price of an off-the-cuff experiment.

However you came down on that piece, though, it was a hell of a night. If anything, our modest but vital local jazz scene is only making gains in excitement value.