Posted: Thu Nov 17, 2011 7:26 am
by KoutaR
Steve,

In addition to Junipeus communis and Alnus incana, there is at least Alnus viridis, though it is more often shrub rather than tree. And if Greenland is in Europe (politically it belongs to Denmark), there is also Sorbus decora, one of the three tree species native to Greenland. I don't know any additional trees native to both Asia and North America.

Of course, the answer depends on the taxonomy. Some authors think the subspecies of Alnus incana and A. viridis are species. And some authors think there is only one Taxus species, for example.

Kouta