Mystery Evening Bloomer - Not a Primrose

Would anybody happen to know the name of this plant? It blooms in the evening and seems to have seed pods at the base of the plant.

 

Evening primrose (Oenothera).

 

I believe it's Oenothera acaulis. One pic can be found at the following site.
http://www.magma.ca/~fredrkng/Ann/Ann_garden05.html

 

Or Oenothera triloba, another one with leaves somewhat reminiscent of dandelion; this species has seedpods at ground-level within the base of the plant (which I think suggests that what appears to be flower stems are actually extended, 8"-10" long styles, right?) I find this plant quite fascinating, as the flowers open at dusk, within about a minute - one can watch them open.
abgardeneer