Thanks Greene! This will be a big step toward identifying it.
I think this is getting really close here. The pods are wrong for the photos of Sesbania drummondii in the database, but the photo for Sesbania herbacea looks really accurate for the plant. Googling for photos of S. herbacea led me to another similar appearing plant - Glottidium vesicarium - where the plant also looks right and the a photo of the seedpods really, really look accurate. The pods ranged from only 1 - 3 beans in a pod with most of them having two beans. The last photo at this site
http://www.sbs.utexas.edu/bio4... is perfect for the dried pods I shelled. They all had that inner membrane around the beans. I'm planning on making an effort to get photos of the plant with pods and blooms to try and get a good identification next year if I'm given the chance. It doesn't seem to be very invasive here. It only grows sparsely down in the dry river bed. On years with enough rainfall that the river runs more often, there is just the occasional plant. The last few years have been leaving the riverbed mostly dry, so there hasn't been any running stream to wash them up and away. I have never seen one growing even half way up the river banks. But in the meantime, I'm going to tag the photo with S. herbacea and G. vesicarium as possibilities. I will note also that along with another Sesbania, S. vesicaria is listed as a synonym for G. vesicarium in the ATP database. So there's something of a taxanomical mix-up somewhere. One drawback to Glottidium is the red in the bloom description. I'm only remembering yellow, so I'm going to have to wait for the blooms. It's not a new plant here. It's been growing in the river bed for years and years.
