The bees will put pollen in the vicinity of wherever the queen goes and wherever they plan or expect to have brood next. They will also put honey on top of the pollen and cap it. So what looks like capped honey, could very well be cell(s) that have pollen in the bottom which are topped off with honey. This can and will occur up the centre column of any of the bottom 3 deep boxes of a langstroth hive. Whether there is a queen excluder or not. The qe certainly reduces the amount above it but does not eliminate it. If one wants very little to no chance of pollen in the honey, which is practically and pragmatically impossible to accomplish, then the only boxes to be extracting are the 4th and above with the qe between the 1st and 2nd box.
An alternative is to run the extracted honey through fine filtration to remove all pollens. But then all that is left is sweetwater.
Academic article specific to this? Not that I've seen or noticed leads on; and I do read ALOT in the off season.
Honey is a mixture of nectar and pollens and the mix is whatever they've been foraging on. The nectar does not necessarily come from the same source as the pollen. Some bees are out collecting pollen, others are out gathering nectar. When they get back to the hive it gets put wherever needed, ultimately all mishmashes together. Why would they gather pollen from a flower that does not yield nectar? Likely because pollen and nectar serve different purpose. Pollen is protein, nutrients, lipids, etc. It is like their cheeseburger! Nectar is raw energy, sugars, ... its like their Coca Cola! Perhaps the crepe myrtle is a very tasty and rich cheeseburger. ;). I've been known to buy my burger at Wendy's then drive 10 blocks to McDonalds to get the coke and fries, just sayin'
What I want to know, on the subject of movement of resources through the hive, ; is if capped honey is not in the optimal place for the wintering nest, why won't they uncap it and move it? My observations indicates that once the honey is capped, that is where it stays. They seem to be very reluctant to touch it and will suffer it up to and including winter death because of it. However, if I simply lightly scratch the cappings then within a day they have moved the entire contents of a full frame to a preferred place. Why is that?