New Riders of the Purple SageWhen: 8 p.m. tonightWhere: Tractor TavernCost: $20MP3: Listen to a sample of New Riders of the Purple Sage’s “Watcha Gonna Do.”From this week’s Short List:Gram Parsons was a cosmic American. New Riders of the Purple Sage are psychedelic cowboys. There’s a difference. In the early ’70s, Parsons was a country-rock pioneer, baking his dreamy croon in the glorious L.A. sun while pumping his fragile Dixie sounds full of Southern California’s favorite drugs: booze, smack, pills, and coke. Meanwhile, 400 miles up the coast, in trippy San Francisco, the New Riders were jamming with the biggest acidheads of them all, the Grateful Dead. NRPS married desert honky-tonk, creamy folk rock, and mutant vibrations from distant Crab Nebulas. Over the years, they’ve released a slew of LPs while going through a seemingly infinite number of lineups. But founding father David Nelson, as well as Garcia’s kick-ass successor, Buddy Cage, has kept the Panama Red burning during the group’s recent resurgence as a live act. — Justin Farrar