According to my copy of Britton & Brown's 'An Illustrated Flora of the United States and Canada' American Mistletoe species are in the genus Phoradendron. Apparently there are around 100 species in this genus - all American and parasitic on broad-leaved trees. There are another 10 species, in the genus Razoumofskya, which are parasitic on conifers. B & B was published in 1913 - so the taxonomy may well be out of date now. The only British species (and possibly the most traditional?) is Viscum album.

Just a request from a Brit: Can you Americans put your f***ing guns away and stop f***ing shooting things???!!! Who knows, one day I might visit your bullet riddled country and might actually survive long enough to see an American Mistletoe.