''Bartonia paniculata'', commonly known as twining screwstem, is a

saprophytic Saprotrophic nutrition or lysotrophic nutrition is a process of chemoheterotrophic extracellular digestion involved in the processing of decayed (dead or waste) organic matter. It occurs in saprotrophs, and is most often associated with fungi ...

annual Annual may refer to: *Annual publication, periodical publications appearing regularly once per year **Yearbook **Literary annual *Annual plant *Annual report *Annual giving *Annual, Morocco, a settlement in northeastern Morocco *Annuals (band), a ...

biennial Biennial means (an event) lasting for two years or occurring every two years. The related term biennium is used in reference to a period of two years. In particular, it can refer to: * Biennial plant, a plant which blooms in its second year and t ...

species that grows in acidic, sandy-peaty wetlands.

Distribution

''Bartonia paniculata'' is the northernmost-ranging species in the genus '' Bartonia''. It is found along the

Atlantic coastal plain The Atlantic Ocean is the second largest of the world's five borders of the oceans, oceanic divisions, with an area of about . It covers approximately 17% of Earth#Surface, Earth's surface and about 24% of its water surface area. During the ...

; its widespread range crosses 29 American states and five Canadian provinces, and overlaps with that of '' Bartonia virginica''. The subspecies ''texana'' is found in eastern Texas and northeastern Louisiana; it was previously identified as ''Bartonia texana''.

Conservation

Twining screwstem is legally protected in the state of

Michigan Michigan ( ) is a peninsular U.S. state, state in the Great Lakes region, Great Lakes region of the Upper Midwest, Upper Midwestern United States. It shares water and land boundaries with Minnesota to the northwest, Wisconsin to the west, ...

as a threatened species. Populations of the subspecies ''texana'' have declined by 50% over the past 57 years. It is found within the baygalls of the coastal plain forests of southeastern Texas. As the baygalls have become rarer as a plant community, the ''texana'' subpopulation has also declined.

References

Gentianaceae Flora of Eastern Canada Flora of the North-Central United States Flora of the Northeastern United States Flora of the South-Central United States Flora of the Southeastern United States {{Gentianales-stub