Heterotheca grandiflora
San Diego Co., CA
Spjut & Marin 15385, June 2003

Heterotheca oregona var. compacta
Siskiyou Co., CA
Spjut 15560; May 2006

Heterotheca sessilflora ssp. bolanderi
Sonoma Co., CA
Spjut 15084, Sep 2002

Heterotheca villosa
Three Peaks Recreational Area, UT
Spjut 16133, Sep 2007

Delgado, G. M. del Socorro Olivares, M. Isabel Chávez, T. Ramírez-Apan, E. Linares, R. Bye and F. J. Espinosa-García.  2001. Anti-inflammatory constituents from Heterotheca inuloides. J. Nat. Prod., 64 (7): 861–864.  “Three new compounds, cadalen-15-oic acid (1), 3,7-dihydroxy-3(4H)-isocadalen-4-one (2), and dicadalenol (3), were isolated from the aerial parts of Heterotheca inuloides (Mexican arnica), together with the known compounds 7-hydroxycadalene (4), 7-hydroxy-4H-3,4-dihydrocadalene (5), 1-hydroxy-1(4H)-isocadalen-4-one (6), 1-hydroxy-4H-1,2,3,4-tetrahydrocadalen-15-oic acid (7), 7-(3,3-dimethylallyloxy)coumarin, caryolan-1,9-diol, and quercetin. The structures of the new compounds were elucidated by spectroscopic methods. The antiinflammatory activities of the extracts and the isolated compounds were evaluated by determining the inhibition of TPA-induced mouse ear edema. The natural products 3, caryolan-1,9-diol, and quercetin were the most active substances tested and displayed dose-dependent activities.”