“New” here means new to me — it’s probably been there for a decade but I haven’t noticed it before. Thanks to Kenny at Berkeley Hort, who instantly told me its scientific and then its common name, I can say with confidence that it’s Centranthus ruber, or Jupiter’s beard. According to Wikipedia, it also has a string of other common names, among them red valerian, spur valerian, and kiss-me-quick.
Again according to Wikipedia, it’s “a popular garden plant grown for its ornamental flowers.” It’s a native of the Mediterranean region that has been naturalized in many other countries. In the U.S. it is “often seen … in urban wasteland,” which describes Cesar Chavez Park rather well. Both leaves and roots are edible, says the same source, but opinions differ as to how tasty they are. The notion that it has medicinal properties rests on confusion with true valerian (Valeriana officinalis).
Its popularity as a garden plant is not shared in South Africa, where it may not legally be owned, imported, grown, moved, sold, given as a gift, or dumped into a waterway. “The plants are deemed to have such a high invasive potential that infestations can qualify to be placed under a government sponsored invasive species management programme. No permits will be issued.” The quality of invasiveness qualifies it as a peer with many other botanical residents of Cesar Chavez Park; indeed, this is almost a minimum survival requirement in our local rapture of ruderals.