Found in the riparian corridor along a very short stretch of the Santa Ana river in Barton Flats.
Rosa (perhaps R. californica or, more likely, R. woodsii ssp. ultramontana):
I'm certain this is Ribes nevadense (Sierra currant, mountain pink currant):
Aquilegia formosa (Columbine, Crimson Columbine, Sitka columbine, western columbine):
Perhaps a Juncus? Maybe even J. effusus (Bog Rush, common bog rush, common rush).