Everybody has been popped now and some of the genders have changed. The males are Mesquite, Hibiscus, Creosote, Agave, Ruellia, Arroyo, Saguaro, Ocotillo, and Cholla.
The probable females are Monsoon, Sequoia, Oleander, Sahara, Lantana, and Bougainvillea.
I'm still going to keep Agave despite him not being the gender I was hoping for. I actually have a nice match for him that complements his possible hets, so it will work out nicely.