The Portland String Quartet has been celebrating its 50th anniversary this season, and the finale, on Sunday afternoon at Woodfords Congregational Church, presented two clear messages. The first is that, after half a century, the ensemble remains at the top of its game, playing with energy, focus and a sense of purpose. The second is that it is devoted not only to revisiting the great 19th-century scores, but to playing contemporary works and rarities as well.

Two of the players, violist Julia Adams and second violinist Ronald Lantz, have been with the quartet from the start, when it was a side project of the Portland Symphony Orchestra’s principal string players. Dean Stein, the first violinist, joined in 2012, and the group’s current cellist, Andrew Mark, joined the quartet this year, and seems to be a good fit.

The centerpiece of its program on Sunday was a vivid, virtuosic set of folksong transformations by Florence Price, a fascinating figure who was unknown to many concertgoers only a year ago. But she had some success in her day: When the Chicago Symphony Orchestra gave the premiere of her Symphony No. 1, in 1933, it was the first time the orchestra – or, for that matter, any major orchestra – played the music of an African-American, female composer.

But Price lived in a segregated America, at a time when works by women of any race rarely got as far as her symphony did. After her death, in 1953, she was quickly forgotten, and much of her music was lost until a couple renovating an abandoned house in Illinois found a cache of scores and papers bearing Price’s name.

Fortunately, instead of discarding the stacks of music, the couple contacted musicologists at the University of Arkansas, who in turn contacted the Center for Black Music Research in Chicago. The center engaged an editor to put the music into shape and get it published, and this season, Price’s music has been turning up all over the country, just as the classical music world is taking a fresh look at the canon and searching for ways to make it more diverse in terms of both race and gender.

Whether every composer and work revived during this period of reconsideration will prove durable, only time will tell. But Price, who studied at the New England Conservatory with George Whitefield Chadwick, is certainly a contender, and her “Five Folksongs in Counterpoint” (1951) proved a knockout on Sunday.

Price did not simply create a set of variations on the folk melodies she chose – “Oh My Darlin’ Clementine,” “Drink to Me Only With Thine Eyes” and “Shortnin’ Bread,” framed by the spirituals “Calvary” and “Swing Low, Sweet Chariot.” Instead, she presented the melodies succinctly at the start of each movement, often in the viola, with other instruments taking them up in different registers and occasionally modulating to different keys as the music unfolded.

But though it was easy to keep track of the tunes, the work’s more salient feature was the dense, adventurously chromatic counterpoint with which Price cloaked these themes. Nothing was predictable, and usually, the textures were so busy and changeable that by the time you grasped the direction Price was taking, she was already pushing the music elsewhere.

It would be hard to imagine a more vigorous case for the work than the performance the Portland players presented. The group’s pacing and balances, to say nothing of the energy they brought to the set, were illuminating and persuasive enough to make a listener eager to search out more of Price’s music.

The excitement of a new discovery sometimes overshadows the more familiar works on a program, but the ensemble seems to have been prepared for that, and took the precaution of digging into Beethoven’s Quartet in A major (Op. 18, No. 5) and the Brahms Piano Quintet in F minor (Op. 34) with the same exploratory zeal they brought to the Price.

The Beethoven, composed in 1801, catches the composer nearly at a point of transition. Only three years later, his “Eroica” Symphony would explode the old notions of compositional propriety, but in his Opus 18 quartets, Beethoven is still observing them, for the most part. The performance, carefully phrased and sculpted, captured the niceties of that style (in the shapely Menuetto, for example), but also picked up on Beethoven’s nascent iconoclasm in the zesty finale.

Brahms’ development was steadier and more gradual, and by the time of his F minor Quintet, he had already found the voice he would refine through the rest of his work. The piano line provides the motivation for much of this work, and pianist Laura Kargul’s contribution brought the right balance of precision and power to a performance that tapped fully into the work’s supercharged Romanticism.

Allan Kozinn is a former music critic and culture writer for The New York Times who lives in Portland. He can be contacted at: [email protected]

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