Do trees really grow in there?

I am fascinated by the trees. Are they really a staple of Westminster Abbey? Must be- because why would you decorate with them. But still seems odd. Again the hats- those amazing hats. Why doesn't america embrace that more? Maybe they are built in staple for British Women to keep people a minimum length away from them. Prince Williams cousin's (Freggie's children) look all grown up and are beautiful young women- with fabulous hats.