Gorse, on the left, is an occasional invasive around Puget Sound and appears much more commonly on Vancouver Island and the Gulf Islands. Broom, on the right, is an invasive in both places. In my travels in Scotland, I never figured why one would dominate in one place, the other in another. On the Isle of Lewis, gorse is dominant, but they appear together on the (derelict) grounds of Lews Castle.