HYB: diploid - tetraploid crosses

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Since I have not seen any posts for a couple days, thought I would ask a question I have been pondering for some time.  These winter days give me time to poke around the web and do a little on-line library research.

I am also cross posting to iris-photos and iris-species. If that is not appropriate, my apologies.  I am new to both groups.  My observation is that iris-photos seems to be mostly TB breeders and the iris-species group has a somewhat wider interest.  Is that accurate?  I know many of you will get this twice.  Sorry.

So my question is: In making crosses of diploid and tetraploid plants, my understanding is most people use the diploid pollen on tetraploid pod parents because some of the pollen cells may be diploid (unreduced) giving rise to viable tetraploid seed.  There seems to be some good evidence of this happening in the literature in a variety of plant groups. (One of the advantages of being emeritus from the University is that I still have electronic library access.)  So what happens to the all the reduced pollen?  Does it germinate and produce pollen tubes, but just not result in viable gametes?  In some cases I know triploid plants are produced, but these seem uncommon in iris.  Is that true?  Any suggestions for some good cold night reading on the subject?

Thanks

Bill