OK, since I can't edit here, a couple of comments--
When I Googled Dahlstedtia again (spelled the same way), I got over
2600 references. Don't know what I did the first time. Anyway, it is
in subfamily Faboideae and is native to Brazil. It is rare in SoCal;
the only one I saw was at LA Arboretum. It had been there for at least
twenty years, so it must take some frost.