Ireland’s We Banjo 3 call their music “Celtgrass.” The description is apt enough: they use not only banjos—generally the old tenor banjo rather than the bluegrass ­five-string type—but also Dobro and mandolin on occasion, and some of their numbers pair an Irish melody with one of American origin (for instance, “The Rocky Road to Dublin” and “The American Polka”).

The fusion is deceptively simple. Adding banjos to Irish music isn’t that tricky, for almost all the instruments of the traditional Irish ensemble came from somewhere else, and the banjo has been in Irish music for nearly a century. The artistry consists in fitting the rhythms of Irish music and bluegrass together: for all the vague claims that bluegrass descends from Celtic roots (it does, but just a little bit), it, like any other American music, includes African American influences that aren’t present across the pond.

As it happens, the two pairs of brothers who make up We Banjo 3 (the non-­strumming fourth member is a fiddler) have long had enthusiasm for various kinds of musical Americana, and they have the chops to put it all together. The big Irish-bluegrass medleys generate tremendous energy of a kind well suited to urban Irish summer festivals around the Midwest, where the band brings crowds to rock-concert levels of intensity. Their version of the charming centuries-old children’s song “The Fox” has more forward momentum than just about any other rendition out there—find the video on YouTube and try to resist.

We Banjo 3 also has quite a few originals in its catalog, generally less traditionally Irish in flavor since the release of their first album, Roots of the Banjo Tree, in 2012. For their latest album, last year’s Haven, they went to Nashville, enlisted bluegrass guitarist Bryan Sutton as producer, and delivered a set of upbeat contemporary bluegrass tunes. The Irish element is still there, and the instrumental “Dawn Breaks” is a masterful four and a half minutes that approaches the Irish-bluegrass mixture in several ways. All the music comes from the band’s own pens, and though lovers of traditional Irish music might miss the deep melancholy the older style can produce, this band is doing things that nobody else has done before.

Their Michigan fan base, already vigorous, has been enlarged by banjoist Martin Howley’s marriage to local fiddle heroine and Chelsea High (and U-M) graduate Kiana June Weber, who posts preposterously beautiful social media photos of her new life in Ireland. Previous We Banjo 3 shows at the Ark have drawn large, young, energetic crowds, and in February they’re back for two nights, the 27th and the 28th.

—James M. Manheim