The sound we use today in "put" isn't [u], it's [ʊ]. Today, it would definitely not be considered an adequate rhyme for [u:]; would you call "look" [lʊk] an inexact rhyme for "Luke" [lu:k]?
On the other hand, I tend to suspect that [u], if it occurred, would be accepted as an exact rhyme for [u:]. Any line-final [u] in a poem would sort of necessarily be promoted to [u:], though.
On an unrelated note, are there areas that use a [lʊv] pronunciation of "love" today? That might explain the to-me odd use of "lurve" in humor.
Thank you for correcting my careless notation. I often forget about the differences between some of the u-sounds, because my native language (Russian) has just one. To me, "look" and "Luke" actually sounds like a passable rhyme, and in general one feature common to nearly everyone who speaks English with a Slavic accent is that they do not distinguish between [ʊ] and [u:]. I know the difference intellectually, and I try to pronounce them correctly, but I probably still get it wrong every now and then.
I believe [ʊ] used to be [u], but I don't remember when this quality change happened.
On the other hand, I tend to suspect that [u], if it occurred, would be accepted as an exact rhyme for [u:]. Any line-final [u] in a poem would sort of necessarily be promoted to [u:], though.
On an unrelated note, are there areas that use a [lʊv] pronunciation of "love" today? That might explain the to-me odd use of "lurve" in humor.