Kansas Wildflowers and Grasses - Fourpoint evening primrose

FOURPOINT EVENING PRIMROSE

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Oenothera rhombipetala Nutt. ex T. & G.

Geary County, Kansas

Biennial or winter annual

Height: 1-4 feet

Family: Onagraceae - Evening Primrose Family

Flowering Period: June, July, August, September

Also Called:

Rhombic evening primrose.

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 to nearly pinnatifid, 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, .8 to 1.6 inches long, short hairy; sepals 4, lanceolate, 2/5 to 4/5 inch long, sparsely hairy; petals 4, yellow, 1/2 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.

Habitat:

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

Distribution:

Throughout Kansas, but principally in central three fifths.

Forage Value:

Deer will eat fourpoint evening primrose.

Comments:

The showy flowers open around sunset and close during the morning. The flowers are pollinated by night-flying moths.

Fourpoint evening primrose inflorescence