Mentzelia albicaulis
Mojave Desert, Soda Mts., Feb 2008

Mentzelia eremophila

California: Mojave Desert, Kern County, Red Rock Canyon State Park
4 April 2017

Mentzelia involucrata
Palo Verde Mts., CA
Spjut16234, 1 Apr 2008

Mentzelia involucrata
wash, Palo Verde Mts., CA
Spjut15851, Mar 2005

Mentzelia laevigata
Klamath NF, CA
South Fork of the Salmon River,
August 2006

Mentzelia laevigata
Near Susanville CA; September 1979

Mentzelia mexicana
Black Gap Wildlife Refuge, TX
Spjut & Marin15082, Nov 2002

Mentzelia multiflora ssp. longiloba
San Bernardino Co., near Cima
April 1973

Mentzelia nitens
Inyo Co., north of Bishop
Photo by Susan Spjut, May 2006

Mentzelia obscura
Inyo Co., Panamint Valley CA
May 2006

Mentzelia obscura
Inyo Co., CA
Spjut 15246, Apr 2003

Mentzelia pterosperma

Utah—Great Basin Desert-Dixie Corridor. Washington Co., Red Mt., ~15 mi north of St. George on west side of Hwy 18; 37º18'31.2", 113º40.53.4", 1382 m.  Sagebrush scrub with scattered juniper. Erect leafy white-stemmed annual with sticky leaves; flowers yellow but mostly in fruit. Locally abundant.  Sample of the entire plant (rt-st-lf-fr). .: Richard Spjut & Paul Burchstead 16353, 21 June 2008

Weigend M.,  J. Kufer and A. A. Müller. Phytochemistry and the systematics and ecology of Loasaceae and Gronoviaceae (Loasales). 2000. Amer. J. Bot. 87: 1202–1210 “A screening for iridoid compounds of 78 of 315 species from all major groups in Gronoviaceae and Loasaceae has been carried out. The results were compared to the systematic concepts in the family and distribution and ecology of the taxa. Iridoids are present in at least some species of all genera screened. Some simple, monomeric compounds (e.g., loganin, sweroside) are found in all major groups of the two families and represent the basic iridoid inventory. Other compounds are restricted to certain taxonomic groups: nine-carbon iridoids (e.g., deutzioside) are restricted to Mentzelia (Loasaceae subfam. Mentzelioideae), hetero-oligomeric iridoids (e.g., tricoloroside methyl ester, acerifolioside) are restricted to two small groups in Loasa (Loasa ser. Macrospermae and ser. Floribundae, Loasaceae subfam. Loasoideae), and oleosides (e.g., 10-hydroxyoleoside dimethyl ester) are restricted to the large genus Caiophora sensu Weigend). The distribution of certain iridoid compounds thus confirms some of the generic limits. Iridoid phytochemistry does not correlate with systematic entities above the generic level nor does it in any way correlate with the morphological evolution of taxa. Conversely, the amount and complexity of iridoid compounds present in taxa correlate positively with the aridity of their habitat and the extent of mammalian herbivore pressure.”