The jam-band nation has spread itself from coast to coast with dozens of festivals, local gatherings and traveling jamborees. The Spirit of Guthrie Tour adds a new dimension to the scene by focusing on Woody Guthrie’s recently discovered writings. A Herculean stable of songwriters–headed by Leftover Salmon’s Vince Herman and including modern-day bass legend Rob Wasserman of Ratdog, free lyrical wordsmith Jim Page, and newbie Theresa Andersson from the tour’s foundation–take to the stage with solo sets and group improvisations on Guthrie’s work. Catch it Wednesday, March 30, 10 p.m. at The Pour House. Tickets are $10; 821-1120 or www.the-pour-house.com.