California Aster (Symphyotrichum chilense). Herbaceous perennial.
These plants have their good side and their not so good side. The not so good is invasiveness: with water, they spread aggresively, zooming all over the garden. The good is that butterflies love them, they’re easy to grow, and they bloom September – October, months not generally associated with native color.
We’ve also seen native bees visiting the flowers, along with predators such as daring jumping spiders and praying mantises. When bloom season is over, the seeds can attract goldfinches.