Leaf:  Alternate, simple; lanceolate to oblong, pointed at the tip, tapering to the base, up to 15  cm long and about 5 cm broad; margins sometimes wavy, with or without small teeth; upper surface green, rough-hairy, pinnately-veined; lower surface hairy with prominent veins; cauline (on the stem) leaves sessile; biennial forming only a basal rosette of long-petioled leaves the first year. 

Flower:  In a crowded cluster along the top of the stem, often branched; blooming June through October; each flower 3.25 cm long, 2.5-5 cm wide, with 4 free, yellow petals, a cross like stigma, 8 stamens, and 4 green, hairy, reflected sepals; opening at dusk and usually closing before afternoon; each flower only lasting 1 night.

Fruit:  Capsule, cylindrical, usually hairy; up to 5 cm long, 3.5 to 6 cm wide near the base; containing many reddish seeds, 2 to 3 mm long.

Stem:  Short with leafy rosette first year of biennial life; sending up 1 or more stems the second year; stems being upright, hairy, and branched; green to reddish; 0.5 to 1.6 m tall.

Form:  Coarse biennial forb, forming basal rosette the first year and becoming many branched the second year. 

Discussion

The genus name is Oenothera, coming from the Greek oinos meaning "wine" and thera which has been interpreted several different ways.  One source says that  thera is "to imbibe", either meaning that eating the roots enables a person to drink more wine, or referring to a similar European plant that was thought to make people like the taste of wine.  Another source says that thera means "hunt" and that the taproot of the primrose smells like wine.  The species name biennis is "biennial", having a two year life cycle.  

Wildlife feed on the entire plants, but especially the leaves and roots.  Night-flying insects feed on the nectar and pollen.  The slight lemony fragrance is attractive to moths, the main pollinators of evening primrose.  Many sphinx moths are attracted to the flowers in central Illinois, looking and acting like hummingbirds as they hover over the flowers.

An unusual name for this plant is "Indian Gum" derived from Native Americans chewing the pith.  Some Native Americans rubbed the roots on the muscles of athletes to give them more strength.

Evening primrose has been used in many herbal remedies over time, treating such symptoms as coughs, sores, wounds, eczema, headaches, and hangovers.  In fact, it was known as the "King's Cure-All" for hundreds of years.

This plant is native to North America.  Evening primrose was introduced to Europe in 1612 as a food plant for its edible roots (when boiled) and young leaves.  

Distinguishing Characteristics

Common evening primrose lacks a 4-sided ovary and capsule, has angular seeds, and calyx lobes adhering to each other; with bright yellow flowers. 

Associated Plants

Common milkweed (Asclepias syriaca), common thistle (Cirsium vulgare), Queen Anne's lace (Daucus carota), and wild lettuce (Lactuca serriola). 

Distribution

Evening primrose is found across most of the United States, particularly in the eastern 2/3 of the country.  This plant can be found in old fields, roadsides, ditches, open areas, waste places.  It prefers dry soil.   

Images

Click each small picture to see a larger image. 

October,2003 SS	October, 2003 MH	October, 2003 SS	October, 2003 SS
October, 2003 MH	October, 2003 MH	October, 2003 SS

Location

N 38.27945°    W -89.89032°       
Found on the central east side of an empty lot between McDonald's and PJ's Tire service on West Main Street in Carlinville, Macoupin County, IL.       

Copyright

Photos © 2003 Megan Harper and Sarah Schlotmann, Carlinville High School, linke@carlinvilleschools.net       
           


References

Ladd, Doug.  1995.  Tallgrass prairie wildflowers.  Falcon Press Publishing Co.,  Inc., Helena (MT).  262 pp.

Evans, Margaret Meissner. 1990.  Green heritage.  Abbott & Foran, Inc., Decatur (IL).  200 pp.

Edsall, Marian S. 1985.  Roadside plants and flowers.  The University of Wisconsin Press, Madison.  143 pp.

Venning, Frank D.  1984.  Wildflowers of North America.  Western Publishing Company, Inc., Racine (WI).  340 pp.

Stubbendieck, James, Geir Y. Friisoe, and Margaret R. Bolick.  1994.  Weeds of Nebraska and the Great Plains.  Nebraska Dept.of Agriculture, Bureau of Plant Industry, Lincoln.  589 pp.

Peterson, Roger Tory and Margaret McKenny.  1968.  Wildflowers.  Houghton Mifflin Company, Boston.  420 pp.

Northern Prairie Wildlife Research Center
http://www.npwrc.usgs.gov/resource/othrdata/plntguid/species/oenobien.htm

Viable Herbal Solutions
http://www.viable-herbal.com/singles/herbs/s837.htm 

The Missouri Flora Website
http://www.missouriplants.com/Yellowalt/Oenothera_biennis_page.html 

Cedar Creek Natural History Area, University of Minnesota
http://www.cedarcreek.umn.edu/herbarium/542.htm 

Wildflowers and Other Natural Wonders of the Southeastern U.S.
http://2bnthewild.com/plants/H204.htm 

Rick Mark.  A Guide to the Wildflowers of Twin Swamps Nature Preserve in Posey County, Indiana
http://www.usi.edu/science/biology/TwinSwamps/Oenothera_biennis.htm

Wayne College, The University of Akron (OH)
http://www.wayne.uakron.edu/nature/dreveningprimrose.htm

 Click here to return to the plant list for Carlinville High School's South-Central Illinois flora studies.