I certainly opened a can of worms, at least for myself, when I started reading about Forestiera species. I had learned about F. neomexicana...
In the summer it’s easy to spot a stand of horsetail milkweed (Asclepias subverticillata) along the side of the road with its slender leafed...
The genus is now Hesperocyparis, but back in the olden days I learned the rough bark Arizona cypress of southeastern Arizona as Cupressus arizonica...