Field of Science

White by Evening in the American Southwest

Though various species of it may be found around the world, the evening primrose family Onagraceae reaches its highest diversity in the south-west of North America. For this post, I'm looking at a genus endemic to this region, Eremothera.

Eremothera boothii, copyright Kerry Woods.

Eremothera is one of several genera of evening primroses newly recognised by Wagner et al. (2007). The species included in this genus had previously been included in the broader genera Oenothera or Camissonia, but these genera were progressively broken down owing to polyphyly and poor definitions. Eremothera species are annual herbs with more or less erect stems. Leaves are arranged on the stem alternately; those near the base are carried on a long petiole of up to six centimetres. The genus is distinguished from its close relatives by having mostly white flowers that open in the evening (in rare cases they my be pink or red, fading as they age). Pollination is by moths when the flowers first open, with small bees visiting the flowers the following morning. The fruit is a long capsule that arises directly from the main stem without a subtending stalk.

Eremothera refracta with flowers and green fruits, copyright Stan Shebs.

Seven species of Eremothera were recognised by Wagner et al. (2007). Eremothera nevadensis is a specialist of clay soil that occupies a relatively small range in Nevada, around Reno. Eremothera refracta is a widespread species in the south-west United States with fruit that are of an even diameter along their length (Hickman 1993). Eremothera chamaenerioides is a self-pollinating derivative of E. refracta with smaller flowers in which the stigma is surrounded and overtopped by the anthers. Eremothera boothii and E. minor (both also widespread) have fruits that are wider at the base than at the tip. In E. minor the inflorescence is held erect; in E. boothii the flowers nod. Two localised species, E. gouldii and E. pygmaea, are self-pollinating derivatives of E. boothii. Eremothera minor is also self-pollinating, and may in some cases even be cleistogamous with pollen being transferred to the stigma without the flower even opening.


Hickman, J. C. (ed.) 1993. The Jepson Manual: Higher Plants of California. University of California Press: Berkeley (California).

Wagner, W. L., P. C. Hoch & P. H. Raven. 2007. Revised classification of the Onagraceae. Systematic Botany Monographs 83: 1–240.


  1. I wondered where the name came from, as I don't recognise the parts. I went to Wikipedia to see if they had anything. Their links for Eremothera on the pages for the species and family all take one to the page for the genus of windscorpions called Eremothera.
    So I looked it up on Perseus and I guess it comes from solitary (like eremite) and the ending of Oenothera, apparently meaning catcher.
    The original oenothera was narcotic and almost certainly not the plant for which we now use the name. Literally "ass-catcher".

    1. The original paper which named Eremothera (as a section of Camissonia) doesn't provide any sort of explanation of the name, so I'm afraid you have to be content with speculation.

  2. Martin H. Muma gave the origin of the name for the windscorpion as "solitary wild animal".
    By the way, there is virtually nothing on about the windscorpion genus if you wanted to bash out a quick twin to this article. Only 4 specimens known in 2006. Both botanical and zoological types of Eremothera are found in Arizona in the US and Sonora in Mexico.
    I read that the family Eremobatidae has "Legs 2,3 :" which can't mean what it seems to mean. Though it might explain why they are not common ;o)

    1. Might be a reference to the terminal spines on the end of the second and third legs of this family. Can't say why it would be phrased that way, though.

  3. I should have written kinds rather than types as I do not know where the herbarium types for Eremothera come from.


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