Wisconsin's rare plants

Twining screwstem is an herbaceous vine. Its inflorescence is a raceme, flowers are small, 2.5-4mm, white to purplish or yellowish, and the petals are lance-shaped. Its fruits are capsules. Its leaves are mostly alternate and scale-like appressed against the stem. The lower leaves may be opposite. It may grow erect or maybe lax and sometimes scrambling or almost twining around other plants or objects.

The leaves on the closely related Bartonia virginica are mostly opposite.

Blooming occurs July through September, fruiting mid-August through early-October.

Annual/biennial. The optimal identification period for this species is late-July through mid-September.

Associated species include Rhynchspora capitellata, R alba, Carex scoparia, C oligosperma, C echinata, Pinus banksiana, Drosera rotundifolia, Viola lanceolata, Xyris species, Juncus dudleyi, Lycopodium inundatum, Muhlenbergia species, Sphagnum species, Eriophorum virginicum, Scirpus cyperinus, Osmunda cinnamomea, and Vaccinium macrocarpon.

Twining screwstem is found in mucky-peaty sand and boggy-sandy meadows. It is strongly associated with the area covered by Glacial Lake Wisconsin.

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.

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.

Minimize disturbance to hydrology, including soil disturbance from rutting.

Maintain and restore open habitat through selective clearing and brushing.

Survey for and control invasive plants prior to conducting timber operations, as these can be spread by vehicles and often respond vigorously to increased light. See forestry BMPs for invasive species.

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.