Northern Evening Primrose Oenothera parviflora: Summer to Fall Yellows

Summary: New World wildflower Northern Evening Primrose is native to Canada and central/eastern United States. Soft yellow flowers open by August and last into fall.

Oenothera parviflora, The Hague, midwestern Netherlands; Monday, Aug. 1, 2005: TeunSpaans, CC BY SA 3.0 Unported, via Wikimedia Commons

Oenothera parviflora is a New World flowering plant native to Canada and the United States.

Claiming homelands in eight of ten Canadian provinces, Oenothera parviflora is absent from Alberta and Labrador as well as from all three territories.

In the United States, Oenothera parviflora ranges across the central and eastern United States from the Upper Midwestern states of Minnesota, Iowa and Missouri eastward to the Atlantic coast, from Maine southward through South Carolina.

Oenothera parviflora is known commonly in English as Northern Evening Primrose or as Small-Flowered Evening Primrose.

Northern Evening Primrose thrives in open, sunny habitats such as fields, meadows, and prairies with dry, sandy soil. Although usually associated with  non-wetlands, Northern Evening Primrose tolerates such wetlands as riverbanks and lake shores.

As a biennial (Latin: bi-, “once every two” + annus, “year”), Northern Evening Primrose both blooms and dies in the second year.

Growing to up to five feet (1.5 meters), Northern Evening Primrose features red-tinged, erect stems. Simple, lance-shaped leaves climb alternately up the stem.

Edged with small teeth or toothless, narrow, red-tinged green leaves exhibit dull white veins, with the central vein’s redness at the leaf’s base quickly transitioning to dull white.

Soft yellow flowers conspicuously open in mid- to late summer and close in mid-autumn.

Four heart-shaped, yellow flowers cup eight yellow, elongated-anthered stamens that surround a bright yellow, cross-shaped pollen receptor known as a stigma.

Four pale, greenish yellow sepals drape noticeably downward along the long, slender floral stalk. Because they are borne below their true tip, sepals feature a small scale, inconspicuous or pronounced as a knob or ridge at the apparent apex, known commonly as end or tip. This tiny projection distinguishes Northern Evening Primrose from its lookalike, Common Evening Primrose (Oenothera biennis), which bears sepals at their true tips.

Fruits emerge as tubular capsules with four flared tips in the leaf axil, the upper angle between stem and leaf stalk. Drying to rusty brown or black, fruit capsules split open upon ripening.

Northern Evening Primrose marks the northern and southern borders of my yard. They unfurl their soft yellow flowers in the lush, compact northern field and in the biodiverse, super-sunny southern meadow.

The flowers’ pretty yellows give gentle greetings in the early morning before closing for the day well before mid-morning. They have been open all night, and daytime is sleep time for Northern Evening Primrose flowers.

native status map of Oenothera parviflora: USDA NRCS (National Resources Conservation Service) NGCE (National Geospatial Center of Excellence) & NPDT (National Plant Data Team), via USDA NRCS PLANTS Database

Acknowledgment

My special thanks to talented artists and photographers/concerned organizations who make their fine images available on the internet.

Image credits:

Oenothera parviflora, The Hague, midwestern Netherlands; Monday, Aug. 1, 2005: TeunSpaans, CC BY SA 3.0 Unported, via Wikimedia Commons @ https://commons.wikimedia.org/wiki/File:Oenothera_parviflora_close_up_flower.jpg

native status map of Oenothera parviflora: USDA NRCS (National Resources Conservation Service) NGCE (National Geospatial Center of Excellence) & NPDT (National Plant Data Team), via USDA NRCS PLANTS Database @ https://plants.usda.gov/home/plantProfile?symbol=OEPA5

For further information:

Chayka, Katy. “Oenothera parviflora (Northern Evening Primrose).” Minnesota Wildflowers > Plants by Name.
Available @ https://www.minnesotawildflowers.info/flower/northern-evening-primrose

Miller, Philip. "Oenothera." Figures of the Most Beautiful, Useful, and Uncommon Plants described in the Gardeners Dictionary. In two volumes: Volume II. London England: John Rivington, MDCCLX (1760).
Available via Biodiversity Heritage Library @ http://bibdigital.rjb.csic.es/ing/Libro.php?Libro=4416&Pagina=67

New England Botany Society. “Oenothera parviflora L. small-flowered evening-primrose.” Go Botany > Simple Key > All other flowering non-woody plants > All other herbaceous flowering dicots.
Available @ https://gobotany.newenglandwild.org/species/oenothera/parviflora/

"Oenothera." Michigan Flora > Onagraceae.
Available @ http://michiganflora.net/genus.aspx?id=Oenothera