Evolutionary advantage?

Very quick blip today. I'm really busy this morning doing all the work I was supposed to do yesterday, so on my way to work I quickly stopped by this tree that caught my eye last week. If anyone can identify it let me know.

I'm fascinated as to why the leaves on this tree have arranged themselves to look like the petals of a flower. To attract insects? Surely it would just have evolved flowers if it wanted to do that. I suppose there's some kind of light-harvesting advantage to be had from being in this configuration? It was growing in a very shaded spot.

Anyway, I thought it was pretty :)


edit: Thanks to Instography and Sea Urchin it looks like this is a hydrangea, and these are its winter flowers. You learn something new every day. Soooo, as far as I'm aware, they're neither petals or leaves, they're bracts. Thanks blipfoto :)