Bartonia paniculata
Panicled screwstem
Image of Bartonia paniculata

Photo by MNFI Staff 

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Key Characteristics

Small saprophytic annual (20-40 cm) of acidic sandy-peaty wetlands; stems very slender, appearing leafless, but with tiny scale-like alternate leaves; flowers pink, tiny (2-4 mm), with 4 petals.

Status and Rank

  • State Status: T
  • State Rank: S2
  • Global Rank: G5


County NameNumber of OccurrencesYear Last Observed
Van Buren11996
Distribution map for Bartonia paniculata

Updated 5/15/2018. Information is summarized from MNFI's database of rare species and community occurrences. Data may not reflect true distribution since much of the state has not been thoroughly surveyed.


Associated with patterned fen complexes, the margins of shallow lakes/intermittent wetlands, within coastal plain marshes, and lakeplain wet-mesic prairies.

Natural Community Types


For each species, lists of natural communities were derived from review of the nearly 6,500 element occurrences in the MNFI database, in addition to herbarium label data for some taxa. In most cases, at least one specimen record exists for each listed natural community. For certain taxa, especially poorly collected or extirpated species of prairie and savanna habitats, natural community lists were derived from inferences from collection sites and habitat preferences in immediately adjacent states (particularly Indiana and Illinois). Natural communities are not listed for those species documented only from altered or ruderal habitats in Michigan, especially for taxa that occur in a variety of habitats outside of the state.

Natural communities are not listed in order of frequency of occurrence, but are rather derived from the full set of natural communities, organized by Ecological Group. In many cases, the general habitat descriptions should provide greater clarity and direction to the surveyor. In future versions of the Rare Species Explorer, we hope to incorporate natural community fidelity ranks for each taxon.

Associated Plants

Bog clubmoss, one-flowered muhly grass, grass-leaved goldenrod, beak-rush, bulrush, bog-buckbean, bluejoint grass, twig-rush, sedges, bushy aster, black-fruited spike-rush, umbrella-grass, northern clubmoss, panic grass, cross-leaved milkwort, bald rush, tall beak-rush, tooth-cup, netted nut-rush, hyssop hedge nettle, marsh St John's-wort, pipewort, autumn sedge, and meadow beauty; shrub margin may include: red maple, black gum, pin oak, black chokecherry, dogwoods, and buttonbush.


Requires conservation of habitat and protection of hydrology, such as the maintenance of cyclical drawdown regime. Maintain moist, open habitat. It may also require natural disturbance such as fire to maintain relatively open habitat. Vulnerable to ORV impacts, dredging, and filling of sites.

General Survey Guidelines

Random meander search covers areas that appear likely to have rare taxa, based on habitat and the judgment of the investigator.

Survey Methods

Page Citation

Michigan Natural Features Inventory. 2007. Rare Species Explorer (Web Application). Available online at [Accessed Aug 16, 2018]

More Information

See MNFI Species Abstract


Survey References

Technical References

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