Oenothera flava (Low Yellow Evening Primrose) - photos and description



The following 4 photos were taken at night using 2 studio lights with a portable power supply.

Oenothera flava

Oenothera flava

Oenothera flava

Oenothera flava

The following 4 photos were taken at night using a flash. The plants began flowering about 45 minutes after sunset, photos taken 90 minutes after sunset in total darkness.

Oenothera flava

Oenothera flava

Oenothera flava

Oenothera flava
Stigma is divided into four linear lobes

The following 2 photos of leaves were taken during the day

Oenothera flava

Oenothera flava
In above photo, leaf underside shown in top half of photo, leaf top side shown in bottom half of photo

General: Prostrate, acaulescent plants whose flowers open at night.

Flowers: Flowers solitary, yellow,  stigma divided into 4 linear lobes. We measured a flower to 2.5 cm wide, petals measured at 12 mm long. At night the flowers open astonishingly quick, we timed one flower opening at night - the process beginning with a slit in the side of the flower bud with a tiny bit of yellow showing, to the flower fully open, took about 9 minutes.

Leaves: Leaves are oblong-lanceolate, long, and deeply incised. Leaf measured at 20 cm long and 4 cm wide. Leaves have a prominent midrib on their underside. Top of leaves with very short hairs, bottom glabrous.

Height: Not applicable.

Habitat: Clay soil on flood plains, slough margins, creek bottoms. Also have observed them in large numbers on the clay soil of hilly, prairie roadsides in the Cypress Hills.

Abundance: Rare, ranked as an S3 by the Saskatchewan Conservation Data Centre.

Origin: Native.

When and where photographed: Photos taken August 28th, 29th, and 30th, flood plain of Wascana Creek, just outside city limits of Regina, SK.