Like a meal in four courses that compliment but don’t overlap, Wednesday’s Roots delivered exquisite versions of four stages of country music evolution. From the sturdy and often elegant string band sound of Tim O’Brien we hyped things up a bit to a (drumless) electric honky tonk vibe with Greg Garing. Chelle Rose, East Tennessee’s answer to Townes Van Zandt, delivered literate, narrative-heavy songs with drums and measures of grungy power. And while less twangy or bluesy than the rest of the flight, Allen Thompson showed us the chemistry that results from a band of friends singing well-crafted songs that march along in classic Americana fashion. It was the first show of a blazing July, but it was a wry heat.