Purple leafed birch

Ever on the look out for unusual plants, I noticed a copse of birches on the Princeton campus which seemed to be late in leafing out. On closer inspection there were leaves on the branches but the leaves were a dark purple in color and not the usual bright green. I tried to Google it to find more information but there's only a palty amount of information about this mutation. Apparently there's something called Betula "Crimson Frost" on a website and a photo of Betula "Royal Frost" that seems to match the photos I took. Not much more information than that.

It seems like it would be a very nice addition to a landscape. Unfortunately we have no more room to plant a nice copse let alone one. A truly sad state of affairs.