Hi nobhodi (good luck with that) ^_^Is haiku an expression of Buddhism — or is Buddhism an adjunct of haiku ?
I'd say that haiku is a product of a complex cultural religious background. Not at all exclusively Buddhist.
Also, since the publication of: Bashō and the Dao: the Zhuangzi and the transformation of Haikai
By Peipei Qiu [sample it here - http://goo.gl/96MNQ]
We have a whole renaisance of Tao ideas back in old Japan (especially the somewhat eccentric wayless way
of Zhuangzi (Chuang Tzu) - who towers beside Laozi, apparently. To break out of the mould of populist poetry forms, the more sophisticated haiki players in the floating world of Edo and precincts, went ape over, what one Benedictine monk nutshelled as (and not without humour): "You enter upon the way of Chuang Tzu when you leave all ways and get lost."
~ Thomas Merton
The great wayless way
traveller himself, Basho, is said to have modelled his entire haiku methodology, to no small extent, on the back of this refreshing new wave of Tao knowledge, in his later years. And who could deny he did an outstanding job with it?
So, you know, my point is, that since the early days of haiku's diaspora and certainly as mediated by the beatniks Zen craze, people have fallen into the trance of inserting haiku into, or proclaiming haiku to be the one and only: 'literature of Zen'
. Clearly this is myopic nonsense.
So, anyway, your initial question is seriously biased and needs qualified. Haiku, whether in its ancient or modern forms, is NOT Buddhist per se at all, you see. This is a folk legend. At best. Certainly we can do haiku through our particular personal and/or cultural filters, sure - but, lets not be duped into thinking this is the heart and soul of this mysterious little form of insight and expression we all dig. Not by a long chalk.