Bartonia virginica (L.) B.S.P.
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Basis for Listing
This diminutive annual belongs to a small genus endemic to eastern North America. Its distribution is centered in the Atlantic Coastal Plain with scattered inland populations. Bartonia virginica reaches Minnesota at the extreme western edge of its range and is generally considered rare or threatened throughout much of the Great Lakes region. The collection record indicates that it has always been rare in Minnesota. The very few records that exist are mostly historical, and are from wetlands located in the east-central portion of the state. Approximately 90% of the species' potential habitat has been converted to agricultural use, so B. virginica has likely suffered a corresponding decline. Given its extreme rarity in the state, B. virginica was listed as an endangered species in 1996.
Bartonia virginica is a very inconspicuous plant, but it is quite distinctive. It is characterized by a wiry stem, with opposite, strongly ascending branches. Leaves are opposite, scale-like, and yellowish green. Flowers are small, yellow, and four-cleft.
The range of habitats that might prove suitable for B. virginica in Minnesota is difficult to determine with precision because of the limited collection records. However, the known occurrences of this species are in conifer swamps and in wet meadows at the edge of conifer swamps. Bartonia virginica seems to prefer areas at least partially shaded by canopies of Larix laricina (tamarack) or Thuja occidentalis (northern white cedar), with ground cover of abundant Sphagnum or Polytrichum spp. (mosses). All known sites supporting this species are located on the Anoka Sand Plain.
Biology / Life History
Bartonia virginica is an herbaceous annual pollinated by small flying insects. There is little additional information available at this time on its life history.
Conservation / Management
The collection record indicates that B. virginica has always been rare in Minnesota and occurs in very low numbers, even in ideal habitat. Its small size and inconspicuous nature makes it very difficult to find, which complicates survey work and population assessments. Even after extensive searches in potential habitats, there is currently only one small population known to be extant in Minnesota. The site is in a conifer swamp in Cedar Creek Natural History Area in Anoka County. The land is protected from direct development, but it could be vulnerable to off-site activities that affect the larger hydrological system of this species' habitat.
Conservation Efforts in Minnesota
The only population of B. virginica currently known to occur in Minnesota is found in the Cedar Creek Natural History Area owned by the University of Minnesota. The site is currently protected from private development projects and road building. The need for further conservation efforts has not been assessed.
Mason, C. T., Jr., and H. H. Iltis. 1965. Preliminary reports on flora of Wisconsin No. 53 Gentianaceae and Menyanthaceae - Gentian and Buckbean Families. Transactions of the Wisconsin Academy of Sciences, Arts and Letters 54:295-329.
Minnesota County Biological Survey. 1995. Natural communities and rare species of Goodhue County. Biological Report No. 44. Minnesota Department of Natural Resources, St. Paul, Minnesota.
Ownbey, G. B., and T. Morley. 1991. Vascular plants of Minnesota: a checklist and atlas. University of Minnesota Press, Minneapolis, Minnesota. 320 pp.
Wovcha, D. S., B. C. Delaney, and G. E. Nordquist. 1995. Minnesota's St. Croix River Valley and Anoka Sandplain:a guide to native habitats. University of Minnesota Press, Minneapolis. 248 pp.