Boromir's search for Imladris

[Inziladun]

Originally Posted by The Mouth of Sauron

So why didn't Boromir just knock on the doors of Isengard and ask Saruman where Imladris was ?

It probably didn't occur to Denethor that Saruman might know.

Though the reader is told that Saruman was the head of the White Council, on which also sat Elrond, there's no indication Denethor was aware of that, or that there was any such thing as the 'White Council'. How would Denethor have guessed the two knew one another?

If Saruman had been a close friend or counsellor of Denethor, I could imagine Denethor asking anyway. Under the circumstances, however, with Denethor being as proud as he was, he probaby just sent his son in the general direction of Imladris, believing he'd find it somehow on his own.