Joni Mitchell, Monday, Pine Knob

CLARKSTON, Mich. - Joni Mitchell has grown blonder, I think, as her music has darkened.

The current Mitchell hair-do flops in a great cascade of luminous curly locks, the brightest thing in the Pine Knob bowl.

The music that came from underneath it probed even further into shadowy corners and around dark bends in the psyche.

EACH STEP of Mitchell's career, from her straight-haired folk singing days through her emergence as a poet and then jazz historian with Charles Mingus, has propelled her nearer to twilight, that most complex time of day.

And that's exactly the time she started at Pine Knob last night, before slightly more than half-capacity.

As duck gathered, Mitchell explored her musical past and present. It was sometimes hard to discern what shape her show was taking or her ideas heading. Yes, a complex time.

MITCHELL'S last album, released in 1982, sampled the strength of the new rock music. When those selections arrived during her stage program, they reached out wider and harder than on album, even with traces of tecno-pop synthetization.

Yet the old familiar tunes were sometimes as challenging, reworked into new shapes rather than standing up to be recognized.

So, if Big Yellow Taxi has regained its original rhythms after its metamorphosis on a previous tour, Born for Robbery suddenly was double-time and rocking while (Playing Real Good) For Free changed to a waltz, and You Turn Me On I'm A Radio took on funkier bass line and drumming.

THE OLDEST song of all, her rediscovered (You're So Square) Baby I Don't Care, from the 1950s, opened up with a techno-pop arrangement and slashing guitar lines. Solid Love, also on that last album, came close to reggae, while Nothing Lasts for Long, with Mitchell trading her guitar for piano, stepped moodily through the slow, quirky rhythms.

So how does all this shape up, in the "miles of aisles" she once mapped out in a live album at the Knob?

A bit murky, I fear.

MITCHELL writes of experience as much as of romance, at the same time she extends her training as a painter into a palette of musical tones and resonances. That combination of instincts, plus her conscious exploration, do not necessarily make for the simplest of shows to comprehend.

She was greeted by a warm but muted response. Her program left out more of her most familiar songs than she put in. And the introspective ballads dammed the momentum at the end, even with a sultry Motown encore of I Heard It Through the Grapevine, a song that lures her sinuous, not-always-precise voice.

"INTERESTING," then - fain praise, perhaps, for a musician whose interests have ranged wide, and endured for so long.