In American rock, supergroups splinter into solo projects and careers; in Irish folk music, the reverse is true. Singers and instrumentalists appear on one another's albums and, when the chemistry's right, form a semi-permanent unit. Thus were created Planxty, the Bothy Band, De Danaan and, more recently, Reel Union.

The group's five members -- singer Dolores Keane, guitarist-fiddler John Faulkner, flautist and whistle-player Sean Keane, piper Eamonn Curran and accordionist Martin O'Connor -- have some 20 album credits among them. While there isn't yet an "official" Reel Union album, two recent offerings show the band's commitment to traditional Irish music.

It helps, of course, that the Keanes (who are brother and sister) and Faulkner are superb singers, and that the group's instrumentals sparkle with virtuosity. "Brokenhearted I'll Wander" beautifully captures the band's folk-chamber esthetic with a series of bouncy jigs, reels and hornpipes, several poignant ballads and some ebullient highwayman songs (the Irish equivalent to cowboy songs). Dolores Keane, who has recorded with both DeDanann and the Chieftains, has a gorgeous voice, wistfully strong and full of rich ornamentation on "Month of January" and "Johnny Lovely Johnny," and subtly supportive of Faulkner's virile approach on "Will Ye Go to Flanders." The most fascinating cut is "Mouth Music/Eddie Curran's Favourite," a provocative mixture of an ancient Scottish singing style -- in vogue when there were no instruments to play and singers had to make do with imitation -- and a vocal technique for learning pipe tunes. Try to sing along!

"Farewell to Eirinn" is an album of songs and tunes that grew out of the massive emigration from Ireland to America that started in the early 1800s and approached the saturation point between 1845 and 1855, when a quarter of Ireland's population -- 2 million people -- left. Most of those who left were victims of unemployment and, of course, the murderous famine that began in 1845. There was always a bittersweet blend of heartbreak at leaving the homeland and anticipation about a new life in the land of promise. "Farewell to Ireland," the melancholy air that opens the album, is echoed again and again in such songs as "The Kilnamartyr Emigrant," "The Farmer Michael Hayes" and "The Greenfields of America," about people who "left a wounded nation for to seek a situation in a land beyond the foam."

Once here, the emigrants never stopped longing for Ireland, and their songs are as much the blues as what came out of America's slave culture. Like both the blues and the English ballad tradition, many of the Irish songs are long and narrative. "Eirinn" is a quietly insightful album about roots. ON RECORD, ON STAGE THE ALBUMS REEL UNION: Broken Hearted I'll Wander (Green Linnett SIF3004) Farewell to Eirinn (Green Linnett SIF3004) THE CONCERT REEL UNION: Wednesday at the Birchmere.