Odd one out

Still have a friend staying. We went for a walk up to Kelston round hill, a favourite, and although it was cloudy it was lovely as usual. Flowers spotted included clematis, scabious, and the seed head of a willow herb, which I hadn’t noticed before - a clever design where the seeds are arranged along tiny stalks which seem back to front to me,  and will no doubt fly off in all directions. I remember walking up there once with a friend who is a geologist; she pointed out that the stones on the pathway (now 220 metres above sea level) used to be the seabed, and had tiny fossilised sea creatures in them. Another mind boggling thing:)
The odd one out is the Persian Silk Tree, which was in a garden beside the A4.  I’d been looking at it for a while, but wasn’t able to stop and take a look, by a busy junction.  Anyway, now I was able to get along there, and unfortunately it was starting to be past it’s best, but still amazing.  I’ve never heard of it, let alone seen one. Hope you can get an idea of it from this.