[Wikipedia] Geographical Distinction: Four varieties are recognized in Malacothamnus fasciculatus, which can be difficult to distinguish morphologically but are mostly distinct geographically. Malacothamnus fasciculatus var. catalinensis and Malacothamnus fasciculatus var. nesioticus are geographically isolated on islands. Malacothamnus fasciculatus var. fasciculatus and Malacothamnus fasciculatus var. laxiflorus intergrade where their ranges meet. (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: 04/02/2025).