Emmenopterys henryi flowering at the US National Arboretum

I've been waiting for blue sky to photograph this but apparently this is a blue as it gets. It's been flowering almost two weeks. It flowered heavily two years ago, then skipped last year. 'That's not enough information to tell us whether it's alternate blooming or just requires an inordinate amount of heat to set buds. We'll just have to keep watching.