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 (yellow bartonia) 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 or urban 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.

  Description

Bartonia virginica is renowned for its small size, simplified structure, and ability to hide in plain sight. Although it is very hard to find, it is distinctive in that it resembles no other plant in Minnesota. It can be as short as 5 cm (2 in.) with as few as 2 or 3 flowers or as tall as 30 cm (12 in.) with a dozen or more flowers. The stem is stiff and wiry and has very small scale-like leaves. The leaves are usually opposite each other on the stem and few in number. Branches will be few, short, and strongly ascending. The flowers may not be immediately noticed as such. They are small, each with 4 inconspicuous yellowish petals. The fruit is an ovoid capsule with numerous minute seeds (Mathews et al. 2009).

  Habitat

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. It 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). The only site currently known is located on the Anoka Sand Plain.

  Biology / Life History

Bartonia virginica is believed to be mycoheterotrophic, meaning it partially relies on a symbiotic relationship with soil fungi to help obtain its mineral nutrients and to take up water. This is especially critical in the seed and seedling stage in the life cycle. This may, at least in part, explain why B. virginica has a minimal root system and no root hairs. However, B. virginica does produce chlorophyll in its leaves and stems, so it is only partially dependent on soil fungi (Cameron and Bolin 2010). Although this life style is unusual among plants, it is not unique to this species.

  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 Ecosystem Science Reserve 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.

  Best Time to Search

The best time to search for Bartonia virginica is in August and September when flowers are more likely to be present. Even with flowers, it is very inconspicuous and easily overlooked.

  Conservation Efforts in Minnesota

The only population of B. virginica currently known to occur in Minnesota is found in the Cedar Creek Ecosystem Science Reserve 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.

  Authors/Revisions

Welby R. Smith (MNDNR), 2020

(Note: all content ©MNDNR)

  References and Additional Information

Cameron, D. D., and J. F. Bolin. 2010. Isotopic evidence of partial mycoheterotrophy in the Gentianaceae: Bartonia virginica and Obolaria virginica as case studies. American Journal of Botany 97(8):1272-1277.

Mason, C. T., Jr., and H. H. Iltis. 1965. Preliminary reports on the flora of Wisconsin No. 53. Gentianaceae and Menyanthaceae - gentian and buckbean families. Pages 295-329 in Berquist, G. F., Jr., editor. Transactions of the Wisconsin Academy of Sciences, Arts and Letters. Volume LIV. Wisconsin Academy of Sciences, Arts and Letters, Madison.

Mathews, K. G., N. Dunne, E. York, and L. Struwe. 2009. A phylogenetic analysis and taxonomic revision of Bartonia (Gentianaceae: Gentianeae), based on molecular and morphological evidence. Systematic Botany 34(1):162-172.

Minnesota County Biological Survey. 1995. Natural communities and rare species of Goodhue County. Minnesota County Biological Survey Biological Report No. 44. Minnesota Department of Natural Resources, St. Paul.

Ownbey, G. B., and T. Morley. 1991. Vascular plants of Minnesota: a checklist and atlas. University of Minnesota Press, Minneapolis. 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.