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.
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.
Stigma is divided into four linear lobes
The following 2 photos of leaves were taken during the day
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 basal, 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 (as of 2021) 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.