The first two tracks on the new Devilish Merry CD, "Water & Vines," could cause disorientation to a folk music fan trying to trace all the roots.

The title song begins simply with a banjo, played Appalachian clawhammer-style, but then the percolating percussion of a Celtic bodhran comes in, followed by the melancholic textures of an alt-country lapsteel guitar. If that's not dizzying enough, by the middle of the minor-key "Bluebird," plaintive Irish fiddle and almost-bluesy tin whistle melt into a traditional Appalachian dance tune, "Cluck Old Hen," previously recorded by the likes of Alison Krauss and Kris Delmhorst.

On top of that, anyone not familiar with Devilish Merry might be amazed to hear the members have been doing this conscious merging of styles since before 1979, when they self-released an LP (reissued on CD in 2000) called "The Ghost of His Former Self," which can still be found by eagle eyes in used record stores and is considered a folk music cult classic.

"We were very driven by the five people having their own backgrounds and personalities," recalls founding member and banjoist Sue Powers. "We fused those interests together even though they didn't relate that closely, and that's why it was good. We had someone like L.E. McCullough, who was an all-Ireland tin whistle champion -- when he came to Pitt, he was in their first graduating class for ethnomusicology."

"He literally wrote the book on how to play the tin whistle," dulcimerist Jeff Berman refers to "The Complete Irish Tin Whistle Tutor," first published in 1976 and still in print today. "It was like the bible of tin whistle playing."

Fast-forward more than 15 years, and the core members of Devilish Merry had moved eastward and not woodshedded for a while. When they decided to start up again, the first few gigs were in the Allentown, Lehigh County, area. "We didn't have McCullough, but [violinist] Jan [Hamilton-Sota] showed up with some folk music friends. It was just like old times -- the magic was there, and the sound was great. Maybe it was the combination of instruments -- it wasn't just about picking up where we left off, because everyone had grown."

With Ms. Powers and husband/guitarist Bob now back in Pittsburgh along with the addition of Mr. Berman (a New York City transplant who at one point played with Peter Stampfel in the Unholy Modal Rounders), the group is once again based near the Appalachian hills. The members are busy with other projects in the music scene -- Ms. Powers and Mr. Berman are in world-fusion trio AppalAsia, Mr. Powers in blues-rockers JJ Burner, and drummer Kip Ruefle splits time between Celtic quartet Callan and rockers Paperback and ATS -- but Devilish Merry has found the energy to release two CDs: 2005's "Beauty Is Everywhere" and the new "Water & Vines."

The group's disparate origins are as apparent as ever. "For me, it was listening to a lot of Irish singers, and that whole British folk scene was important to us, like Richard Thompson [of Fairport Convention] and Bert Jansch [of Pentangle]," recalls Ms. Powers. "We were blending it with estern Pennsylvania Appalachian music, and smashing it all together because we didn't have any choice."

More recently, they've added a touch of psychedelic freak-folk -- Mr. Powers mentions listening to Espers or indulging in a bit of Captain Beefheart.

The band occasionally follows that chemtrail -- on the track "Crash Site," Mr. Powers' guitar effects sound like a laser gun or a UFO taking off while his wife sings, "Did you find another kind of intelligent mind?"

But the primary element that makes Devilish Merry unusual is the prominent banjo, which is "frailed" (a variant of the clawhammer rhythmic picking technique) by Ms. Powers. "It's like an Afro-blues style applied to Celtic music. I'm almost destroying the banjo's identity so that it can be used in this other kind of music."

"It's polyrhythmic, not like a tenor banjo or acoustic guitar just used to strum a melody," adds Mr. Berman. "The clawhammer style [explores] inside the rhythm, not just at the bottom or something on top, and there's a rolling, churning feeling to the music."

Folk music fans might remember, says Mr. Berman, that the traditional American hillbilly repertoire originated in the British Isles, and that the banjo arrived by way of Africa. Ms. Powers remembers being impressed by country-blues musician Taj Mahal, who played the banjo. "Jan and I opened up for him as a duo, and I was into him since high school. The contribution of African music to Appalachia was a real black-white fusion thing, which seems so obvious now."

Devilish Merry's instrumental "Toure's Farewell" indicates the modern pollination moving across the Atlantic. "For the last 40 years, there's been this incredible back-and-forth with guitarist Ali Farka Toure and the Malian players influenced by American blues, while British players like Thompson, Jansch and John Renbourn were affected by American music in their search to get back to their own roots," Mr. Berman says.

That cross-cultural exuberance will be in evidence tonight at the Thunderbird Cafe, when Devilish Merry celebrates the release of "Water & Vines" with two long sets. The quintet of Berman, Hamilton-Sota, Ruefle and the Powerses will be joined by playwright McCullough ("he lives in New Jersey and is coming to town because his wife is performing at Carlow in a play he wrote," explains Ms. Powers), uilleann piper Bruce Foley (of Hooley and Guaranteed Irish), Sheila Liming (of Callan) on accordion and Scottish parlor pipes, and new bassist Jeremy MacDonald (the bassist on the disc is Sam Matthews, also of garage rockers Brass Chariot).

According to Ms. Powers, the addition of bass acclimates Devilish Merry to a more mainstream audience that isn't used to the lack of low end in folk music. With a sound not traditional enough for the Calliope audience, nor straight-ahead pop enough for the WYEP crowd, and with older members too disconnected from any local psych-folk underground, the group must find its own niche out of sheer necessity.

"Bob and I are art-school kids, and when you apply that kind of thinking to music, you want to do something that's novel and personal," Ms. Powers says. "It's inherent in Appalachian music that each person has this incredible style, which they chalk up to living alone in a 'holler' far away from everyone else."

Anyone who criticizes Devilish Merry for not being "traditional" enough is taking the music too seriously, adds Mr. Ruefle, especially in the age of the Internet, when Celtic, Appalachian and African music all have a global fanbase, and it's increasingly difficult to be a hermit in a shack next to a moonshine still. "The music was never meant to end up behind glass in a museum -- the tradition is always growing and evolving."

Critics Andrew Druckenbrod and Scott Mervis talk about music on "The Beat," available exclusively at PG+, a members-only web site of the Pittsburgh Post-Gazette. Our introduction to PG+ gives you all the details.