One of the great formative influences of contemporary popular music, Joni Mitchell was the first woman of her generation to show that a songwriter does not need to use or to be a male narrator, to describe the world. Yet her relationship to the women who have ploughed the musical field she helped to pioneer, has been complex. She refuses to identify with them, saying, "People tend to lump me always with women... they don't put Dylan with Men of Rock: why do they do that to me with women?"

The first wave of this new generation had appeared in the 1970s with Rickie Lee Jones and Joan Armatrading. The repetitive 'new Joni' refrain soon became tiresome for both the original and her alleged imitators. Jones has admitted that there was rivalry with Mitchell, fuelled in part by her own frustrations at emerging onto the music scene, feeling vibrant and original, only to be labeled as a clone. Jones has said, "We did have a kind of war going on - she called it the War of the Berets. I'd heard that Joni was not fond of me because of things I'd said earlier in my career... things people say when they've just come out and they try to discredit everyone who came before them."

Suzanne Vega - who led the '80s wave - also found the lazy comparisons inaccurate. She had embraced urban neo-folk, inspired by Lou Reed not Joni Mitchell. But Suzanne readily acknowledges, "Joni has had an enormous impact on not only music but on culture in general. She was experimenting with song forms and using African rhythms as far back as the mid 70s, which is something everyone does now with hip-hop, fusing folk narratives

with a groove." Shawn Colvin sees the Joni link as a compliment rather than a curse: "I truly feel that if anyone were to say 'you are the next Joni Mitchell,' you were influenced by Joni Mitchell's I'd say yes! That would be complimentary. She was one of the first women, if not the first, to be so massively wonderful that there should be no gender about it."

Mitchell's longevity and insistence on self-determination, her unwillingness to go against her internal grain - even when to do so would have made her career more lucrative - made her a powerful role model for feminism. But here is the paradox: the woman whose entire creative path has been a model of feminist strength, who has acknowledged that sexism lies at the heart of disrespectful treatment by the media and industry, whose songs oppose violence against women and encourage independence, is openly critical of feminism and of other women. Musician Ani DiFranco once interviewed Mitchell and in her article, despaired: "She even cites the breakdown of the family and says children are not playing in backyards anymore ' because their 'mothers are not at home', implicating feminism and no other social or economic circumstances, as the cause."

Despite the contrariness and the paradoxes, Mitchell deserves to be celebrated. Her strengths owe nothing to blonde ambition or men. She has maintained complete artistic control over her music, publishing and artwork; she has made most of her albums without the intervention of a producer; she has never been afraid to take risks, to make mistakes, to lose fans, radio play and video exposure - the very things that the industry insists you must never do. At 57, old enough to be Britney Spears' grandmother, Joni is a living experiment in how women can maintain a creative life through their forties, fifties and beyond.

Karen O'Brien's biography of Joni Mitchell: 'Shadows and Light - Joni Mitchell' is published by Virgin, October 4. Karen is a member of Women in Music.