Synonyms

Claytonia caroliniana var. spatulifolia, Claytonia caroliniana var. lewisii

  Basis for Listing

Claytonia caroliniana is distributed in the Appalachian Mountains from northern Georgia through New England; in the northern portions of the Great Lakes states; in the northwest corner of Arkansas; and from southwestern Newfoundland across southern Quebec and Ontario (Davis 1966; Kartesz 2010). In Minnesota, C. caroliniana is fairly narrowly distributed within 30 milesof Lake Superior. There is one historic outlier twice that far inland, an 1893 collection from Tower, Minnesota.

When C. caroliniana was designated a special concern species in Minnesota in 1984, this small woodland plant was believed to be largely restricted to old-growth, northern hardwood forests along the North Shore of Lake Superior. While the species' range is limited to extreme northeastern Minnesota, targeted rare plant surveys over the past two decades have resulted in the discovery of many more populations in a broader range of forested habitats. Claytonia caroliniana is now known to be more common and widely distributed in Minnesota than was formerly believed, and it has been proposed for delisting.

  Description

Claytonia caroliniana is a low-growing, woodland perennial. The stem elongates as new flowers develop at the tip and can be 6-25 cm (2.4-9.8 in.) long. Flowers are 8-12 mm (0.31-0.47 in.) in diameter and petals are pink to white, with pink veins (Davis 1966). Several flowers per stem are arranged in a raceme (Fassett 1976). Leaves are somewhat succulent, oval- or lance-shaped, and distinctly narrowed to the petiole (leaf stalk). The flowering stalk bears 2 opposite leaves. Various sources differ on the number of basal leaves present, with 0-3 (Davis 1966), 1-few (Gleason and Cronquist 1991), and 6-21 (Miller 2003) reported. Leaves are up to 8 cm (3.1 in.) long and up to 3 cm (1.2 in.) wide, with stem leaves generally longer and narrower than basal leaves (Miller 2003).

  Habitat

Almost all occurrences of C. caroliniana in Minnesota are found in the Northern Superior Uplands ecological section with a handful of occurrences in the Southern Superior Uplands. Within that narrow distribution, C. caroliniana is found in forest types ranging from mesic, to wet-mesic, to wet. It is most frequently found in northern mesic hardwood (cedar) forests (ca. 65% of observed locations) followed by wet forests (ca. 20% of observations). Some of the wet sites with sparse tree canopies might be classified as alder swamps. Several occurrences were also found in northern mesic mixed forests, and one occurrence was in a cliff community. Other habitats mentioned by observers included pine plantations, logged areas, and roadsides. Typical canopy tree species include Acer saccharum (sugar maple), Betula alleghaniensis (yellow birch), B. papyrifera (paper birch), Populus tremuloides (trembling aspen), Abies balsamea (balsam fir), and Fraxinus nigra (black ash). Associated shrub and herb species include Alnus incana ssp. rugosa (speckled alder), Streptopus lanceolatus (rose twistedstalk), Carex pedunculata (long-stalked sedge), and Clintonia borealis (bluebead lily). Sometimes C. caroliniana grows mixed with C. virginica (Virginia spring beauty).

Soils where C. caroliniana is found tend to be moist or wet. Observers often described them as loamy with a thick layer of leaf litter. Variations to loam soils included rocky loam, loamy clay, and rocky soils; one site had peaty soils. On sites where the species was distributed across more than one native plant community, C. caroliniana tended to be more abundant where the soils were wetter.

  Biology / Life History

Claytonia caroliniana is a spring ephemeral adaptated to survive in reduced sunlight conditions of forests with dense canopies. This group of species takes advantage of the early spring to capture and store most of their annual energy needs before the tree leaves open fully (Minnesota DNR 2003). Claytonia caroliniana stores energy in underground globose tubers that are 1-2 cm (0.4-0.75 in.) in diameter (Davis 1966; Miller 2003). Many of the known populations are quite large numbering in the hundreds and thousands of plants.

Claytonia caroliniana can grow in deep shade, partial shade, and full sun. However, the proportion of flowering to non-flowering plants is greater in areas where there is more sunlight. Deeply shaded areas tended to have fewer flowering plants. Claytonia caroliniana is insect pollinated, although specific pollinators are not known. A C. virginica population in North Carolina was pollinated by a solitary fly species and a bee fly species (Motten et al. 1981). Seeds are spread short distances as the seed capsule breaks open and throws the seeds away from the plant (Schemske 1977).

According to Davis (1966), C. caroliniana and C. virginica seldom occur in the same locality. However, in a New York state population, Doyle and Doyle (1988) documented hybridization of the two species. In Minnesota, co-occurrence of the two species has been noted in two areas of Cook County.

The best time to search for C. caroliniana is in May. A few Minnesota collections have been made as early as April and as late as mid-June, but most observations of C. caroliniana were made in May and early June. Occasionally plants were in full flower as early as May 3rd. By June, the leaves are typically dying back or senescing, which makes the plants harder to see.

  Conservation / Management

The effects of forestry management practices on C. caroliniana are unknown, but some forestry activities, especially ones that cause compaction, rutting, or other disruption of the ground layer; result in any drying out of the habitat; or convert a native plant community to a plantation, are the greatest threats. Other potential threats include recreational activities, trail development, invasive species, and development in northern Minnesota. The best way to protect this species is to protect and manage the sites where it is known to occur.

  Conservation Efforts in Minnesota

Over half of the observations of C. caroliniana are on public land, including many on land owned by the U.S. Forest Service. About 20 are owned by the Minnesota DNR. Targeted searches for this plant were a successful conservation strategy as it enabled biologists to ascertain that the species was not as rare as it was once thought to be.

  References

Davis, R. J. 1966. The North American perennial species of Claytonia. Brittonia 18:285-303.

Doyle, J. J., and J. L. Doyle. 1988. Natural interspecific hybridization in eastern North American Claytonia. American Journal of Botany 75:1238-1246.

Fassett, N. 1976. Spring flora of Wisconsin. University of Wisconsin Press, Madison, Wisconsin. 424 pp.

Gleason, H. A., and A. Cronquist. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. Second Edition. New York Botanical Garden, Bronx, New York. 910 pp.

Kartesz, J. T. 2010. The Biota of North America Program (BONAP). North American Plant Atlas. <http://www.bonap.org/MapSwitchboard.html>. Accessed 18 January 2011.

Miller, J. M. 2003. Claytonia. Pages 465-475 in Flora of North America Editorial Committee, editors. Flora of North America north of Mexico. Volume 4. Oxford University Press, New York, New York.

Minnesota Department of Natural Resources. 2003. Field guide to the native plant communities of Minnesota: the Laurentian mixed 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. 352 pp.

Motten, A. F., D. R. Campbell, D. E. Alexander, and H. L. Miller. 1981. Pollination effectiveness of specialist and generalist visitors to a North Carolina population of Claytonia virginica. Ecology 62:1278-1287.

Schemske, D. W. 1977. Flowering phenology and seed set in Claytonia virginica (Portulacaceae). Bulletin of the Torrey Botanical Club 104:254-263.