I have been reading a gardening book originally written in the 1940s; the author mentions about an annual Centranthus, C. macrosiphon, with pink flowers similar to the perennial C. ruber, but she indicates the folige is different.
I found very little information about this species in the internet search I conducted. I found one reference that called it "Pink Valerian" but couldn't locate much else.
I successfully grew C. ruber from seed this year, and am curious about this annual species.
Does anyone have more information, photos (or seeds) to share?