This tree is in the Japanese garden on the Pacific National Exhibition grounds. All leaves are trifoliate. Some leaves are serrated and some are not. Pedicels are long and red. Bark is grey and smooth. I hadn't realized (or remembered) that Acer cissifolium is native to Japan, so it would be appropriate here. I'm looking for confirmation that I have this right, else the correct ID. It's really all those unserrated leaflets that make me question this. Thanks.
It looks like A. cissifolium. Older wood producing leaves with entire margins would suggest A. henryi, but it appears that the new and 2nd-year wood here is still red; in this late season new shoots should be turning greenish, and 2nd-year shoots should be dark green, if it were A. henryi. That's the giveaway between the two species.