Canadian singer-songwriter Roberta Joan Anderson? Most shoulders will shrug. But before the trauma of giving up a child conceived the night she lost her virginity, and a short-lived marriage which gave her a new surname, this is who Joni Mitchell used to be.

Seventy-three today, Mitchell has a life story that reads like a tabloid sensation. A sickly childhood. Huge fame. Rock-star lovers (Graham Nash, James Taylor). A disease in later life, Morgellons, dismissed by many professionals as delusional; a brain aneurysm earlier this year, from which she is slowly recovering. Then there are the songs known the world over, including "Little Green", about the daughter with whom she would later, but only briefly, reunite.

Childhood polio meant Mitchell couldn't play guitar chords easily, hence her unusual finger-picked style. She developed her bright, direct voice as an art student. She started writing her own songs to get away from her husband, Chuck Mitchell; she'd married him in 1965 to forge a family unit for the baby she had from an earlier relationship.

"If you make a bad marriage," she once said, "you become a philosopher." Mitchell's philosophies arrived in quicksilver melodies, and lyrics full of personal weight and strange poetry. In "Both Sides Now", clouds used to be "rows and flows of angel hair/And ice cream castles in the air"; now they "only block the sun/They rain and snow on everyone." It was this blend of beauty and honesty that radiated from her 1971 masterpiece, Blue.

Mitchell was also hugely forward-thinking. Her 1975 song, "The Jungle Line", presaged Björk. The avant-garde jazz phase that began around that time never lacked heart. And while there were some lacklustre late-20th-century albums, she achieved a career highlight with 2007's Shine, which showcased her rougher, slower, but still hugely affecting voice. Drama has always whirled behind the scenes, but the woman within has always stood tall.