Basis for Listing

Silene nivea has a scattered and discontinuous distribution largely limited to a few states in the Midwest. It is apparently uncommon throughout most of its range, with several states reporting declining populations. Silene nivea was not added to the first official state list in 1984 because it had not been seen since 1939, and was thought extirpated in Minnesota. Since 1984, highly directed field surveys have been conducted, which resulted in the discovery of a handful of relatively small populations. This confirmed that the species still survived in Minnesota, but that it is very rare. Based on these results, Silene nivea was ultimately listed as a state threatened species in 1996.

  Description

Silene nivea is a showy plant, but it may not be immediately conspicuous in its preferred habitat. Flowers are few, scattered, solitary, and divergent in the upper leaf-axils. The white petals are slightly notched and have a small crown on the upper surface near the base. The calyx is 5-toothed and more or less inflated over the capsule. There are 10 stamens and a 1-locular capsule. The leaves are sessile and have a thin, attenuated tip. The stems are glabrous, long, and slender (Gleason and Cronquist 1991). Because the stems of S. nivea are long and slender, they often lean on other vegetation, almost vine-like.

  Habitat

In Minnesota, S. nivea occurs only in the southeastern corner of the state. It seems to prefer partial openings in alluvial forests and meadows. The species has also been found in seepage areas, and in one case, at the edge of a calcareous fen.

  Biology / Life History

Silene nivea is an insect-pollinated, perennial herb. Sexual reproduction is accomplished by seed, although the mechanism of seed dispersal is not known. Asexual reproduction is important to population maintenance, and is accomplished by the growth of long rhizomes. Rhizomatous growth can result in the formation of fairly large clones. It is possible that some populations may consist of a single clone even though there may be numerous autotrophic individuals (ramets). In such a case, each individual would be genetically identical to all other individuals in the population.

The best time to search for S. nivea is when it is in flower in July.

  Conservation / Management

Forested river valleys where S. nivea naturally occurs have been largely cleared of native vegetation and planted with row crops; where terrain is not suitable for cultivation, livestock is often pastured to the detriment of native vegetation. As a result, there is very little riverine habitat in southeastern Minnesota that sustains significant examples of native vegetation. Where populations of S. nivea are found in native habitats, it is important to maintain the natural conditions, especially the natural cycle of spring flooding.

  Conservation Efforts in Minnesota

The Minnesota DNR County Biological Survey has been completed in the likely range of this species in the state.

  References and Additional Information

Hitchcock, C. L., and B. Maguire. 1947. A revision of the North American species of Silene. University of Washington Publications in Biology 13:1-73.

Minnesota County Biological Survey. 1994. Natural communities and rare species of Houston County. Minnesota County Biological Survey Biological Report No. 50. Minnesota Department of Natural Resources, St. Paul.

Minnesota County Biological Survey. 1994. Natural communities and rare species of Winona County. Minnesota County Biological Survey Biological Report No. 49. Minnesota Department of Natural Resources. St. Paul.

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.

NatureServe. 2021. NatureServe Explorer [web application]. NatureServe, Arlington, Virginia. (https://explorer.natureserve.org/). Accessed 29 July 2021.

Schlising, R. A., and H. H. Iltis. 1961. Preliminary reports on the flora of Wisconsin. No. 46. Caryophyllaceae - pink family. Pages 89-139 in S. D. Beck, editor. Transactions of the Wisconsin Academy of Sciences, Arts and Letters. Volume LI. Wisconsin Academy of Sciences, Arts and Letters, Madison.