[Wikipedia] Range, Habitat: Viola hallii is a species of violet known by the common names Oregon violet and Hall's violet. It is native to southwestern Oregon and northwestern California, where it occurs in open areas in the forests and chaparral of the coastal mountain ranges, on gravelly soils, often of serpentine origin. (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: 04/05/2025).
