I did a cut test of five.

The first thing you needed to do was pick them mature but still soft and green. Now that they are hard and brown you will have to wait the maximum amount of time for dormancy to be overcome.

Years ago I read about taking the embryos of this particular species out of the seed coats and sprouting them on a moist surface before planting in soil. Apart from the dormancy that comes with the hardening of all maple seeds paperbark maple has a problem with some of the sprouting embryos not being able to escape the shells - look how thick they are in your picture.

Really no more tricky to germinate than Acer palmatum.....the issue is most of the seed is empty/sterile/or otherwise non-viable. Typically a 20% viability rate is quoted and I doubt whether cross pollination really ups the odds much at all. A local mature paperbark (50+ years) is a prodigeous seed producer - the samaras literally cover the ground under it at this time of year - but only around a half dozen actually germinate on their own and the owner hasn't had much better results when handling them directly

From Dirr's guide to propagation: Cold stratify seed for 90 days, split the fruit wall, extract the embryos and plant them in a vermiculite-peat mix.

There is only the single specimen in the location I am referring to and yet it manages to produce a few - not many - spontaneous seedlings every year.

I know that for Metasequoia, better quality seed has been coming directly from wild trees in China.

Does this help for Acer griseum?