Philadelphia pianist extraordinaire Dave Burrell is a "civic treasure." Ideally, to keep said description fresh, those two words should only come together when truly warranted. Like now. Such a reference to Burrell and his 70th-birthday-celebrating engagement last week at the Philadelphia Art Alliance (an urbane gem itself), presented by the invaluable Ars Nova Workshop (another sterling effort), seems essential.

Accompanied by the sympathetic, world-class talents of William Parker on bass and Philly native Sabir Mateen on flute, sax, and clarinet, Burrell led his trio through expansive, now-stormy / now-sweet sets of manifestly felt improv on Thursday and again Friday, his actual birthday. (The latter concluded with a standing ovation for the newly christened septuagenarian - and cake, Parker and Mateen conjuring a sing-along-suitable "Happy Birthday to You" before a quick, free-squallin' outro.)

The consistently excellent pianist ("Bur-rell," accent on second syllable - no streaky former Phillie he) has taught locally (Penn, Swarthmore, etc.) and long inspired internationally. As musician-in-residence at this city's unique Rosenbach Museum & Library, he has composed and performed works inspired by research into the institution's priceless documents, creatively crossing historical interpretation with original music. (Burrell will present another world premiere there in January: "Jazz Portraits of Civil War Heroes," with accomplished local violinist/teacher Odessa Balan.) His illustrious history of collaborations with jazz greats continues today - Parker's years-in-making new release I Plan to Stay a Believer: The Inside Songs of Curtis Mayfield, featuring Burrell and Mateen, is now out - and Burrell appears on more than 115 albums, including 30 under his own name. (This summer's romantic Dave Burrell Plays His Songs Featuring Leena Conquest marries the Ellingtonian elegance of his piano to poet Monika Larsson's words, as sung by vocalist Conquest.)

Above all, Dave Burrell is a renowned, formidable player, expressing so much through his keyboard manipulation that terms such as "neoclassical" or even "free jazz" feel limited, if applicable. On Friday, always attuned to Mateen's breathy, piercing flute runs or elephantine sax blasts and Parker's plucked/bowed bass, Burrell simultaneously effected nuanced leadership and complementary flow, finger-pecking individual ivories, daubing in melodic color, or purposefully mashing multiple keys with the back of his hand - rolling, swelling, utterly engaged, irresistibly engaging.