Rare Species Guide

  Synonyms

Silene drummondii

  Basis for Listing

Silene drummondii ssp. drummondii is basically a species of dry, sandy, prairie or prairie-like habitats where conditions might be described as semi-arid. There is no shortage of this type of habitat on the Great Plains where the species is more common, but it is in short supply in Minnesota. Habitats here generally get more rainfall and have better soils, which leads to denser vegetation. Infrequently, conditions come together to create suitable habitat for this species but such habitats are often small, and they are vulnerable to destruction by a number of land use practices. Silene drummondii ssp. drummondii was listed as a special concern species in Minnesota in 1996.

  Description

Silene drummondii ssp. drummondii is a taprooted perennial with 1 or more erect, viscid-glandular stems around 46 cm (18 in.) in height. The basal leaves have long petioles but the stem leaves are sessile and opposite each other, resulting in 2-5 relatively widely-spaced pairs. They are linear to linear-lanceolate in shape, 3-9 cm (1.2-3.5 in.) long, and 2-7 mm (0.08-0.28 in.) wide. They are also rather stiff and have appressed hairs on both surfaces. The inflorescence is strongly glandular and has 3-10 flowers, which are held on stiffly erect pedicels 0.1-5 cm (0.04-2.0 in.) long. The calyx (sepals) of each flower is broadly tubular to narrowly ellipsoid in shape, and is not inflated as in some species of Silene. It has 10 veins, and is 12-18 mm (0.47-0.71 in.) long and 4-8 mm (0.16-0.31 in.) wide in fruit. The 5 triangular lobes are 1.2-2 mm (0.05-0.08 in.) long. The corolla (petals) is off-white to dusky pink, equaling the length of the calyx.

There are two subspecies of S. drummondii in North America, ssp. drummondii and ssp. striata, but only ssp. drummondii occurs in Minnesota. It is characteristically a prairie taxon, while ssp. striata is associated with the Rocky Mountains (Morton 2005). There are approximately 11 species of Silene in Minnesota, and all are similar in appearance. Silene drummondii ssp. drummondii differs from the others in that the petals are shorter than the calyx so they are not directly visible.

  Habitat

The consistent features of S. drummondii ssp. drummondii habitats in Minnesota seem to be dry, sandy soil and direct sunlight. But the species only occurs where these conditions are present in relatively high-quality native plant communities of dry prairies (northern and southern) and dry savannas (northern and southern). It apparently does not occur on roadsides, agricultural land, gravel pits, or other habitats that have been created incidental to human activities. Suitable habitats are in places that are often described as dunes, savannas, barrens, or pine woodlands. In pine woodlands, the soils are too poor to support a dense forest so the trees are small and widely spaced, allowing a somewhat prairie-like flora to develop in the sunlit openings.

  Biology / Life History

Very little is known about the biology and life history of S. drummondii ssp. drummondii other than what can be inferred from its physical structure and the habitats where it is found. It is perhaps reasonable to assume it is tolerant of drought, but not tolerant of shade or competition from aggressive plant species. The flower structure is indicative of a species pollinated by flying insects, probably moths and long-tongued flies. The fruit is a dry capsule rather than a berry, drupe or nut, indicating it is intended to ripen and disperse seeds while still attached to the plant. The seeds themselves are small and numerous, and do not possess any specialized structures designed to aid dispersal. It is likely that the seeds fall to the ground near the parent plant when the dried capsule is shaken by the wind.

The best time to search for S. drummondii ssp. drummondii is when it is in flower or fruit from June through August.

  Conservation / Management

We have relatively little experience with management of dry, sandy grasslands in Minnesota. It seems they have traditionally received less attention than the more diverse and complex mesic grasslands - sometimes with regrettable consequences. Sandy grasslands (the habitat of S. drummondii ssp. drummondii in Minnesota) also appear to be very popular with owners of off-highway vehicles (OHVs), especially where they exist as small patches of public land in a larger matrix of private agricultural fields. The problem is that wherever OHVs go, invasive plant species follow; Euphorbia virgata (leafy spurge) and Centaurea stoebe (spotted knapweed) are among the worst. The unnaturally lush and aggressive growth of native shrubs that often follows the suppression of wildfires should also be considered a threat to S. drummondii ssp. drummondii.

  Conservation Efforts in Minnesota

Most of the habitats of S. drummondii ssp. drummondii occur on privately owned land. There are currently five sites that are in public ownership, all Wildlife Management Areas that are under the jurisdiction of the Minnesota Department of Natural Resources. The sites are managed for public hunting, which need not be incompatible with management of S. drummondii ssp. drummondii. However, the effects of current management practices on S. drummondii ssp. drummondii are not being monitored.

  References and Additional Information

Morton, J. K. 2005. Silene. Pages 166-214 in Flora of North America Editorial Committee, editors. Flora of North America north of Mexico. Volume 5. Oxford University Press, New York, New York.