Rutaceae, Thamnosma montana - Turpentine broom

Host plant for desert black swallowtail, Papilio polyxenes coloro. It's counterpart in the eastern US, Papilio polyxenes asterius, feeds mainly on plants in the carrot family - parsley, dill, and relatives. Even their caterpillars look different. Yet recent DNA work has shown they are nearly identical genetically!

 

Joshua Tree National Park

Done