Initially the two Arizona state tree palo verdes were the genus Cercidium. That’s the way I learned them and that’s the genus name you’ll find in all the older floras and field guides. Well, not that older, and anyway, Parkinsonia (the Linnaeus name) was the genus of just the Mexican palo verde, Parkinsonia aculeata. Sometime in the 1980s — I think, I dunno, feeling older— when it was realized that all three paloverdes were similar genetically and since Parkinsonia had been named first, that name had priority. Dropping Cercidiun was hard, but hey I got over it and I love…