Wisconsin's rare plants

Yellow evening primrose is an erect forb with yellow, 4-parted flowers that only open in the morning. Petals are 5-12mm long, floral tube 4-angled, funnel shaped, half as long as the ovary, and covered in small hairs. Stigma are broad and shield-shaped. Its fruits are linear, roundly 4-angled, 1.5-3cm long, and are covered with white or gray hairs. Its leaves are alternate, simple, numerous, oblong to linear to inversely lance-shaped, 2-6cm long x 7mm wide with very small, remote, sharp teeth.

It can be distinguished from other Oenothera species by its broad and shield-shaped stigma not having 4 linear lobes.

Blooming occurs late-June through early-September, fruiting early-July through early-October.

Perennial. The optimal identification period for this species is late-June through early-October.

Associated species include Juniperus virginiana, Andropogon scoparius, Aster species, Helianthus species, Solidago rigida, Stipa spartea, and Potentilla arguta.

Yellow evening primrose is found mostly on steep bluff prairies along the Mississippi and lower St Croix Rivers, as well as cedar glades and, occasionally, in moist prairies.

Avoid known individual plant locations and conduct operations elsewhere when they are least likely to cause damage. Ideally, this would involve frozen, snow-covered ground. However, in areas of the state where frozen conditions are unreliable, very dry soils late in the growing season might be the best available alternative. Consult with a biologist, if needed.

Avoid broadcast spraying of herbicides and use care with spot spraying.

Avoid locating landings, staging areas, or access routes in open sandy areas dominated by native grasses.

Prescribed burns and/or brushing may be beneficial, dependent on local site conditions and burn frequency. Rotational burns with annual unburned refugia may be preferred.

Maintain and restore open habitat through selective clearing and brushing.

Species of Greatest Conservation Need (SGCN) are associated with habitats (or natural communities) and places on the landscape. Understanding relationships among SGCN, natural communities and ecological landscapes help us make decisions about issues affecting SGCN and their habitat and how to respond. Download the Wildlife Action Plan association score spreadsheet to explore rare species, natural communities and ecological landscape associations

Conservation actions respond to issues or threats, which adversely affect species of greatest conservation need (SGCN) or their habitats. Besides actions such as restoring wetlands or planting resilient tree species in northern communities, research, surveys and monitoring are also among conservation actions described in the Wisconsin Wildlife Action Plan because lack of information can threaten our ability to successfully preserve and care for natural resources.