The Douglas fir, Pseudotsuga menziesii, is widespread in the Pacific Northwest and the Rocky Mountains, and as such is quite important ecologically. It's not the least distinctive of trees, either, with its tall straight trunks and the conspicuous bracts like three-tailed ribbons poking out of its cones. For all that, though, this tree can be said to have no real name of its own! Both its common name and its Latin name are made entirely of references to other species.
Let's break that down, shall we? We'll start with the common name, "Douglas fir". "Douglas" refers to David Douglas, the botanist who first brought the species to Europe and more specifically to Scone Palace in Scotland. It's not a name for the plant itself -- it's a name for the man who made it famous. "Fir" is also a misnomer, since Pseudotsuga menziesii is not a true fir. True firs belong to the genus Abies; they have (among other things) upright cones that shatter as they ripen, no bracts on their cone-scales, and longer, softer needles that leave circular leaf-scars. Douglas "fir" has hanging cones that stay intact as they ripen, conspicuous bracts on the scales, and shorter, sharper needles that leave oval scars. "Douglas fir" is neither Douglas nor a fir.
The Latin name is no better. "Pseudotsuga" means "false hemlock": it states only that the species resembles the hemlock trees of genus Tsuga but is not in fact one of them. "menziesii" refers to Archibald Menzies, a globetrotting botanist of some renown, who was the first European to collect a great many North American plant species. Again, it's a name for a person, not the plant. "Pseudotsuga menziesii" is neither a Tsuga nor Menzies.
It has a few other names, but they are still not its own. An older Latin name, Pseudotsuga taxifolia, means "false hemlock with yew leaves". "Douglas pine" is no better than "Douglas fir": Pseudotsuga is no more a true pine than it is a true fir. "Oregon pine" is even worse, since the tree's natural range stretches well beyond Oregon.
This species has been formally known to Western science since at least 1889. You'd think that in over a hundred years, someone would at least have given it a name of its own.
Thanks to Barbara Ertter for pointing out this bit of trivia.
Sources: FNA, IPNI