Portland, Ore.-based string-music collective Black Prairie is a spinoff, formed in 2007, of the indie folk band The Decemberists. (Jason Quigley)

In addition to featuring a sound that’s delightfully crossbred — Gypsy-grass? Jewish mountain music? — Black Prairie plays instruments that look like Darwinian accidents.

At Iota Club & Cafe Friday night, singer-violinist Annalisa Tornfelt sometimes played a phonofiddle — basically, a violin with a horn growing out of it — whose antique tone captured the whimsical musicology of this Portland, Ore.-based string-music collective.

Black Prairie is a spinoff, formed in 2007, of the indie folk band the Decemberists. Yet judging from the healthy audience it attracted Friday, it is steadily carving out its own niche in the universe of traditional-minded hipsters. Relying initially on instrumental jams, the band is increasingly employing Tornfelt’s ethereal vocals to great effect, as on the tenderly melodic “What You Gave Me” and “Lay Me Down in Tennessee.”

Improvisatory mastery and adventurousness remains at the heart and soul of the band, however. Chris Funk switched between dobro, banjo and autoharp. Guitarist Jon Neufeld played American bluegrass and, with equal flair, jazz licks in the style of Django Reinhardt. Upright bassist Nate Query and drummer John Moen tag-teamed with astonishingly versatility, lending supple rhythmic support to everything from the cajun-flavored “Dirty River Stomp” to the Appalachian-clogger sensibility of“For the Love of John Hartford.” Gluing it all together was Jenny Conlee’s warm and funky accordion.

The song “Richard Manuel,” a homage to the multi-instrumentalist of the Band, seemed to be a clue to Black Prairie’s secret sauce. Like the Band, Black Prairie is eclectic and yet deeply rooted, place-oriented yet cosmopolitan.

Take the musical spirit that emanated from Big Pink in the late ’60s, plant it in European soil, and you’ll have some idea of the magical cocktail that Black Prairie is serving.

Galupo is a freelance writer.