Carex pallescens L.
Carex pallescens var. neogaea
Basis for Listing
This unusual sedge is primarily an eastern species with rare or infrequent occurrences in the Great Lakes region. When it was listed as endangered in Minnesota in1996, it was believed that within Minnesota it was restricted to specialized habitats near the shore of Lake Superior (North Shore Highlands Subsection). Records seemed to indicate that Carex pallescens (pale sedge) had always been rare in Minnesota, but that it had probably suffered a significant decline corresponding to habitat loss. It seemed to be particularly vulnerable to impacts from rural and suburban development projects, especially road building, road maintenance, and certain high-intensity recreational activities. Subsequent to it being listed as endangered, a small number of occurrences were discovered in rather non-specific habitats (Laurentian Mixed Forest Province) that were previously thought unlikely to support this species. Some of these habitats were not associated with Lake Superior and had evidence of past human disturbance. The status of this species may warrant a revaluation during the next list revision.
What first catches the eye about C. pallescens is likely to be the 2 or 3 green cylinder-shaped spikes clustered at the top of a stiff, sharp-edged culm. The perigynia are tightly packed and each has a broad rounded apex. There is no hint of a beak at the tip, just a circular opening for the style. Also, the bracts of the lateral spikes often (not always) have a series of transverse wrinkles near their base. This is not a unique feature, but it is absent in the closely related C. torreyi (Torrey’s sedge).
Technical description: Culms cespitose, to 75 cm long, sharply 3-angled in cross-section; distal portions scabrous. Rhizomes less than about 1 cm long or not discernible. Leaves flat, to 4.2 mm wide, shorter than the culms; sheaths and abaxial surface of blades sparsely to moderately pubescent; lower sheaths brown to pale brown, sometimes tinged with red, not ladder-fibrillose. Terminal spike staminate, 0.5--2 cm long; peduncle 2--10 mm long. Lateral spikes pistillate, 2--3(4) per culm, 0.9--2 cm long, loosely clustered; peduncles 3--15 mm long. Lowest bract glabrous or minutely scabrous, longer than the inflorescence. Pistillate scales oblong-ovate, about as long as the perigynia, acute or short-awned. Perigynia glabrous, broadly ellipsoid, 2.4--3 mm long, 1--1.6 mm wide, finely veined; apex rounded, beakless; base broadly tapered. Achenes trigonous; style deciduous. Maturing mid-June to late July (Smith 2018).
Most Minnesota populations of C. pallescens occur on the margin of fire-dependent forests of Pinus spp. (pine), Picea spp. (spruce), Populus spp. (aspen), and Betula spp. (birch) adjacent to the Lake Superior shore. Within this forested matrix, C. pallescens seems to prefer low, moist, grassy or rocky habitats at the edge of the forest where it receives partial sunlight. It has also been found in roadside ditches and artificial openings along the shore, but such occurrences may not represent viable populations. There are a few recent records some distance west of Lake Superior in Itasca and Koochiching Counties. Not much is known about these recent records, but they seem to be in shallow wetlands of recent, anthropogenic, origin.
Biology / Life History
Carex pallescens is a wind-pollinated perennial. It does produce short rhizomes (underground stems), but they do not allow the plant to spread any great distance. Dispersion appears to rely solely on the production and dissemination of seed-like achenes. It produces approximately 50-150 achenes each year, which are shed in midsummer. The mechanism by which these achenes get from one place to another is largely unknown but may involve water or animal transport.
Conservation / Management
The only Minnesota habitats where C. pallescens has been observed for extensive periods of time are near the shore of Lake Superior (North Shore Highlands Section), a region that has been experiencing unprecedented increase in development in recent years. The pattern of development has resulted in the incremental loss of habitats that may be vital to the survival of this species in Minnesota.
It seems likely that this species relies on a system of meta-populations. This means that several or many colonies may need to exist over a relatively large area, possibly hundreds of square miles. Within this area, individual colonies would come and go over a period of time. This might happen when suitable habitats change through natural vegetation succession and newer habitats are created from stochastic weather or ecological perturbations. This concept would forgo the need for establishing small nature preserves to protect each colony in favor of managing a larger area to maintain ecological processes that sustain a diversity of habitat.
The recent discoveries of C. pallescens occurring west of Lake Superior are believed to be of recent origin and may not be stable populations. Their role in sustaining this species in Minnesota is unknown.
Best Time to Search
The best time to search for Carex pallescens is in July, when perigynia are mature.
Welby R. Smith (MNDNR), 2020
(Note: all content ©MNDNR)
References and Additional Information
Ball, P. W., and A. A. Reznicek. 2002. Carex. Pages 254-572 in Flora of North America Editorial Committee, editors. Flora of North America north of Mexico. Volume 23. Oxford University Press, New York, New York.
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.
Lakela, O. 1954. Previously unreported plants from Minnesota with additional place records of rarities. Rhodora 56:39-41.
Ownbey, G. B., and T. Morley. 1991. Vascular plants of Minnesota: a checklist and atlas. University of Minnesota Press, Minneapolis. 320 pp.
Smith, W. R. 2018. Sedges and rushes of Minnesota: the complete guide to species identification. University of Minnesota Press, Minneapolis. 696 pp.