[Wikipedia] Hybrid Info, Flower Info: In Britain and America, it is often found as a hybrid of black knapweed, Centaurea nigra.[3] Unlike the black knapweed, the flower heads always look as if they are rayed, forming a more open star rather than a brush-like tuft. (link added by Mary Ann Machi)
Calflora:
Information on California plants for education, research and conservation,
with data contributed by
public and private institutions and individuals.
[web application]. 2025.The Calflora Database
[a non-profit organization].Available:
https://www.calflora.org/(Accessed: 03/28/2025).
one or more occurrences