Robert Plant may seem an unlikely Americana artist. But the educated know the original Band of Joy-which he and future Led Zeppelin drummer John Bonham played in, as well as Zep-was more than profoundly influenced by what drifted across the pond. Plant's latest solo album, "Band of Joy," follows in the fertile vein of 2007's Grammy Award-winning "Raising Sand" with Alison Krauss. The new set incorporates an edgier, resonant kind of ambience from producer Buddy Miller, a more aggressive female vocal foil in Patty Griffin and (on several of the 12 tracks) a greater ensemble attitude. The material is just as fascinatingly diverse, from the trancey flow of Los Lobos' "Angel Dance" to doo-wop-by-way-of-Nashville treatment of the Kelly Brothers' "I'm Falling in Love Again," and the swampy but spare groove that frames the mid-19th-century poem "Even This Shall Pass Away." A pair of Low songs-"Silver Rider" and "Monkey"-are solidly in the wheelhouse Plant is working here. And the Plant-Miller original "Central Two-O-Nine" is a train song so authentic in tone that it almost sounds like a Johnny Cash chestnut. Plant has steadfastly resisted a return to the Zep fold; "Band of Joy" makes us glad for that.