Biennial or winter annual of waste ground and open
habitats. This species and several closely related ones
are difficult to distinguish and, consequently, they are
sometimes referred to as the O. biennis complex.
An appendage on the sepal tips is used in the
identification of this species. The ovary is
rounded or weakly 4 angled. Second year plant
produces a tall raceme of 4 petaled flowers
which open in the evening.
In the long-term experiment
on seed germination by
Dr. W.J. Beal of
Michigan State University, seeds of this
species were still viable after 80 years of
storage.
