Vocal power with an aggressive edge

'Kiss With a Fist," the 2009 single from Florence and the Machine's debut album

Lungs

, made it clear from the get-go that flame-haired British vocal powerhouse Florence Welch was not a demure sort.

"You hit me once, I hit you back," sang Welch, who will lead her five-piece band at the TLA on Monday on the opening night of their first proper American tour. "You gave a kick, I gave a slap/You smashed a plate over my head/Then I set fire to our bed."

"When I started writing the songs on Lungs, I was hanging out with a lot of art-college punk bands," says Welch, 23, talking on the phone from New York. "They weren't singing about sunshine and roses. They were singing about a lot of dark elements. I wanted to write songs to rival the boys. I didn't want to write girly songs. I wanted to write tough stuff, basically to impress the guys," she says with a laugh.

The aggressive edge of "Kiss With a Fist" left a slightly misleading first impression of Lungs, which won best-album honors this year at the Brits, the United Kingdom equivalent of the Grammys. After the pummeling "Kiss," the often death-obsessed Lungs moves into more fanciful, artier territory on tracks such as "Rabbit Heart (Raise It Up)" and "Girl With One Eye," leading inevitably to comparisons with Kate Bush.

Welch is flattered: "I'm a massive fan. But honestly I don't think we sing alike, and our themes are different. I guess maybe it's the dancing," she says, referring to her penchant for losing herself in ecstatic motion on stage.

Instead, she points to the commanding and more typically aggressive PJ Harvey as an influence. "I saw her perform all by herself," Welch says. "And it was the most mesmerizing thing. So vulnerable at some points, and so powerful. It's really an intoxicating combination."

Lungs has been out in the United Kingdom since July, so Welch has already started writing the follow-up. "I would say I'm trying to move away from the gothic horror of the first album," says the singer, daughter of an English adman and an American Renaissance scholar. Lungs, she says, "is quite bodily fixated, anatomically and animally. I'd like the next one to be less entrenched in darkness. I guess I've always been interested in expressing a feeling, but not putting it in so many words, and trying to turn it into something else."

Welch has been writing new songs for a follow-up album with (also redheaded) bandmate Isabella Summers and her producer, Paul Epworth. "We've been writing on the road," says Welch, "so we're recording in hotel rooms and backstage, using cheap equipment." Before going back into the studio, "I'm trying to amass a really big body of work," she says.

One new song is called "Strangeness and Charm," after the names physicists give to the properties of certain quarks. "They're so small that you can't see them, but you know they exist because you can feel their effects. I thought that was a good metaphor for love, affection, that type of thing."

In the United Kingdom, Welch has become a household name rather suddenly. "It was a lot of hard work, though," says the singer, who kick-started her career when she followed her future manager into a public bathroom and sang Etta James' "Something's Gotta Hold on Me" for her. "We spent a lot of time playing the pubs and clubs. That's what I want to have happen here: To have people come out and see me play live. Because that's the best way to understand what the album is all about. That's when it all makes sense."