Clarkia is a showy annual that you might recognize from many of our open spaces. In years with good winter moisture, the hillsides (particularly on Mt Jumbo in our area) practically turn pink with vast swaths of clarkia. Clarkia takes advantage of spring moisture to bloom and set seed, and the plants die when the soils dry. They are reliable seeders though, and planting 3 - 5 in relatively close proximity should provide a stable colony from one year to the next. Clarkias will turn any irrigation you give them into more flowers, so you can control how thick your clarkia patch is.