Chaenactis artemisiifolia
Peninsular Ranges, CA
Spjut & Marin 15319,
May 2003

Chaenactis carphoclinia
California—Inyo Co.: SW of Lone Pine, Cottonwood Road
4 May 2008

Chaenactis douglasii
Kern Co., CA. Piute Mt
30 Apr 2005

Chaenactis fremontii
Forming complete cover on rocky ground, not yet in flower, Chuckwalla Mts., CA
Spjut 15848, Mar 2005 

Chaenactis fremontii
NW of Sheephole Mts., CA
Mar 2005

Chaenactis fremontii
Joshua Tree Natl. Park, CA
Mar 2005

Chaenactis fremontii
Kingston Range, CA
Spjut 1561, May 2003

Chaenactis fremontii
W Mojave Desert, CA
Spjut 15207, Apr 2003

Chaenactis fremontii.  Anza Borego St. Park.  Photo by Sally Larsen
Mar 2005.  Note: This species is recognized by noticeably larger flower around the perimeter of the flower head.

Chaenactis fremontii
with Malacothrix glabrata
~4.5 miles N of Palm Springs, CA
April 1973

Chaenactis glabriuscula
Kern River Canyon, CA
Spjut 15205, Apr 2003

Chaenactis glabriuscula
Kern River Canyon, CA
Apr 2005

Chaenactis stevioides

California—San Bernardino Co.,
between 29 Palms and
 Blythe, Spjut 15754,
Mar 2004

Chaenactis suffrutescens

California—Klamath Region. Siskiyou Co.: Scott Valley, South Kidder Creek west of Greenview on north side of Hwy 3, between Ft. Jones and Etna; 41º32'27.5", 122º54.26.4", 860 m.  Open wide gravel creek bed. Perennial with white flowers; common along gravel bar.  Sample of entire plant. Richard Spjut & Paul Burchstead 16339, 12 Jun 2008

Chaenactis xantiana

California—Los Angeles Co.,
Western Mohave Desert Lake Elizabeth Rd, east of lake, abundant. , 24 Apr 2014. Pappus scales 4 long and 4 short in 2 series.

Constabel C. P. and G. H. Towers.  1989. The complex nature of the mechanism of toxicity of antibiotic dithiacyclohexadiene polyines (thiarubrines) from the Asteraceae.  Planta Med. 55(1): 35–37.  “Thiarubrine A, a dithiacyclohexadiene polyine from the roots of Chaenactis douglasii, and a related dithiacyclohexadiene from Rudbeckia hirta exhibit strong light-independent antibacterial and antifungal activity. This activity is enhanced by exposure to visible light. Visible light also converts the compounds to the corresponding thiophenes. These are antibiotic only when irradiated with UV-A. Dithiacyclohexadienes are the first polyines to exhibit such complex mechanisms of toxicity towards microorganisms.”