By now Sheryl Crow has made enough albums, and earned so many millions of radio “impressions,” that her appeal and smarts could easily be taken for granted. Wildflower, though, is a twist on her L.A. studio rock – one that puts listeners on notice that she’s not about to go quietly. Don’t look at her less seriously because of unabashedly lighthearted hits like “Soak Up the Sun,” this album says; in fact, it’s a reminder that even her breakout single “All I Wanna Do” had a lot more than happy days on its mind. Like Aimee Mann, Crow’s music is rooted in ’70s sounds, and Wildflower reflects a downbeat, wondering tone in nearly every cut. At the same time, it’s also easy to hear vintage Fleetwood Mac, reminding us that pure pop can be escapist and challenging at the same time.