Paronychia canadensis (L.) Wood
Canada Forked Chickweed
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Anychia canadensis, Anychia dichotoma , Paronychia dichotoma
Basis for Listing
Paronychia canadensis (Canada forked chickweed) is a small herbaceous annual of dry and sandy woodlands. In Minnesota, it is associated with oak or jack pine savannas in the southeast (Blufflands Subsection). All five locations have been documented in Houston and Fillmore counties, and one of the populations has not been successfully relocated since it was last observed in 1920. The species’ extreme rarity was known when it was designated a threatened species in 1996; however, it was hoped that more populations might be found with additional surveys. A comprehensive botanical survey of the region was subsequently completed by the Minnesota Biological Survey, and unfortunately no additional populations of P. canadensis were located. Additionally, the known populations are threatened by habitat loss and degradation. Current threats include residential developments, vegetation changes that remove open microhabitats, and conversion to agriculture, including tree plantations. For these reasons, the status of P. canadensis was elevated from threatened to endangered in 2013.
Paronychia canadensis is a small spare-looking plant. The stems are erect, dichotomously branched, 3-40 cm (1-16 in.) tall, and smooth. The leaves have slender stipules, 0.5-4.0 mm (0.02-0.16 in.) long; the blades are usually dotted or blotched, elliptic to obovate in shape, 3-30 mm (1-12 in.) long, and glabrous. The flowers are very small, only 0.9-1.3 mm (0.04-0.05 in.) long; they are pale in color and occur singly. The fruit is a smooth ovoid to globose utricle, about. 0.5 mm (0.02 in.) across (Hartman et al. 2005).
In Minnesota, P. canadensis is found in dry and sandy oak or jack pine savannas, often on slightly raised river terraces in partial sun. It is associated with Quercus velutina (black oak), Quercus macrocarpa (bur oak), Pinus banksiana (jack pine), and a variety of forbs and grasses.
Biology / Life History
Each P. canadensis flower produces a bladder-like fruit, which contains one shiny round reddish-black seed, about 1 mm (0.04 in.) in diameter. An annual, it depends upon a good seed crop or a well-stocked seed bank for a population to return the following year (Core 1941; Great Plains Flora Association 1986). This species is often found growing along animal trails or in other microsites where the sandy soil has periodic disturbance that keeps competing vegetation sparse.
Conservation / Management
The loss of habitat due to rural development and conversion to agriculture appears to be the greatest threat to this species. Restoration plans for native savannas ought to consider the needs of this species. Known locations need to be managed with a cautious regimen of prescribed fire and must not be used as pastures.
Best Time to Search
The best time to search for P. canadensis is when it is in flower, from late July through September.
Conservation Efforts in Minnesota
The Bluffland counties of southeastern Minnesota were surveyed for rare plants in the 1990s by the Minnesota Biological Survey. Many of the Fillmore County plants occur on the Rushford Sand Barrens Scientific and Natural Area, which affords a high degree of protection and increases the likelihood of ecologically appropriate management.
Welby Smith, MN DNR, 1988, 2008 and 2018
Coffin, B., and L. Pfannmuller, editors. 1988. Minnesota's endangered flora and fauna. University of Minnesota Press, Minneapolis. 473 pp.
Core, E. L. 1941. North American species of Paronychia. The American Midland Naturalist 26:369-397.
Great Plains Flora Association. 1986. Flora of the Great Plains. University Press of Kansas, Lawrence, Kansas. 1,402 pp.
Hartman, R. L., J. W. Thieret, and R. K. Rabeler. 2005. Paronychia. Pages 30-43 in Flora of North America Editorial Committee, editors. Flora of North America north of Mexico. Volume 5. Oxford University Press, New York, New York.
Minnesota County Biological Survey. 1994. Natural communities and rare species of Houston County. Minnesota Department of Natural Resources, Biological Report No. 50, St. Paul, Minnesota. 13 pp.
Minnesota Department of Natural Resources. 2005. Field guide to the native plant communities of Minnesota: the eastern broadleaf forest province. Ecological Land Classification Program, Minnesota County Biological Survey, and Natural Heritage and Nongame Research Program. Minnesota Department of Natural Resources, St. Paul, Minnesota. 394 pp.
Minnesota Department of Natural Resources, Division of Ecological Resources. 2008. Rare species guide: an online encyclopedia of Minnesota's rare native plants and animals [Web Application]. Minnesota Department of Natural Resources, St. Paul, Minnesota. Accessed 1 July 2009.
Minnesota Department of Natural Resources, Division of Fish and Wildlife. 1995. Statement of need and reasonableness in the matter of proposed amendment of Minnesota Rules, Chapter 6134: endangered and threatened species. Minnesota Department of Natural Resources, St. Paul, Minnesota. 336 pp.
Ownbey, G. B., and T. Morley. 1991. Vascular plants of Minnesota: a checklist and atlas. University of Minnesota Press, Minneapolis, Minnesota. 320 pp.
Voss, E. G. 1985. Michigan Flora. Part II: Dicots (Saururaceae-Cornaceae). Cranbrook Institute of Science Bulletin 59 and the University of Michigan Herbarium. University of Michigan, Ann Arbor, Michigan. 727 pp.