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Fourpoint Evening Primrose

Fourpoint Evening Primrose
Oenothera rhombipetala 
(Order Myrtales, Family Onagraceae)


 

Photos by David Sanchez, 2011
Diagnosis:
Height: Total height 1.0-2.6' (30-80 cm) tall.
Stems: Erect, simple or branched, hairy.
Leaves: Alternate, simple; rosette blades narrowly oblanceolate, 1.2 to 3.2 inches long, 1/12 to 3/4 inch wide, margins wavy-toothed nearly pinnatifld, petioles often as long as blade; stem leaves oblong-lanceolate to lance-ovate, 3/4 to 3.2 inches long, often crowded, margins nearly entire to remotely toothed, surface hairy, petioles short or absent.
Inflorescences: Spike, 4 to 12 inches long, dense, terminal.
Flowers: Floral tube slender, 0.8 to 1.6 inches long, short hairy; sepals 4, lanceolate, 2/5 to 4/5 inch long, sparsely hairy; petals 4, yellow, 1/12 to 1 inch long, rhombic-ovate; stamens 8, shorter than petals; style as long or longer than petals; stigma 4-lobed.
Fruits: Capsule, cylindric, often curved, tapering toward tip, 2/4 to 4/5 inch long, short hairy; seeds in 2 rows in each compartment, reddish brown.


Flowering Period: June, July, August, September.

Habitat: Stream valleys, roadsides, and waste areas; sandy soils.


Comments: The showy flowers open around sunset and close during the morning. Night-flying moths are the primary pollinators. Evening primrose is eaten by deer, and it can be either biennial or winter annual.


Conservation status: Not threatened.


Distribution: Throughout Kansas, but principally in central three fifths. http://plants.usda.gov/java/profile?symbol=OERH
 

Video: Evening Primrose Flowers

Links:
Oklahoma Biological Survey:  http://www.biosurvey.ou.edu/posters/eveningprimrose.html
eNature.com:  http://www.enature.com/fieldguides/detail.asp?recnum=WF2012
YouTube: Evening Primrose Flowers: http://www.youtube.com/watch?v=DiODdt8l108
Minnesota Wildflowers:  http://www.minnesotawildflowers.info/flower/fourpoint-evening-primrose

References:
Haddock, Michael John 2005. Wildflowers and Grasses of Kansas. University Press of Kansas, Lawrence, Kansas.
Great Plains Flora Association 1986. Flora of the Great Plains. University Press of Kansas, Lawrence, Kansas.


Image Credits:
Four-Point Evening Primrose in the field. Photo by David Sanchez, 2011. p 607.
Four-Point Evening Primrose Close-up. Photo by David Sanchez, 2011. p 44.


Submitted by: David Sanchez, July, 2011.

Wichita State University
Generated on 2011. This website is continuously updated.
Comments can be sent to Mary Liz Jameson.
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