[Wikipedia] Taxonomy: The genus is named after A.J. Downing (1815 - 1852) a noted American horticulturist and landscape architect. (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]. 2024. Berkeley, California:The Calflora Database
[a non-profit organization].Available:
https://www.calflora.org/(Accessed: 11/21/2024).