Rare Species Guide

  Synonyms

Carex garberi var. bifaria, Carex garberi ssp. bifaria

  Basis for Listing

When Carex garberi (Garber’s sedge) was first proposed as endangered in Minnesota in 1984, it was known in the state by a single herbarium specimen. That specimen was collected in 1947 in St. Louis County about 48 km (30 mi.) north of Duluth (North Shore Highlands Subsection) by the botanist, Olga Lakela. Her specimen was initially identified as the similar C. aurea (golden-fruited sedge) and her label described the habitat as a swampy area on Highway 53. Several years later, Lakela's specimen was correctly determined to be C. garberi. Because that particular site had never been relocated, it was unclear if the species still survived in the state. In 1992, it was found in Kittson County (Aspen Parklands Subsection) in an extensive open sedge fen complex. This discovery confirmed that its occurrence in the state was not a fluke.

In 1996, C. garberi was officially listed as threatened in Minnesota. Botanical searches since then have resulted in only two additional occurrences (Laurentian Uplands and Tamarack Lowlands subsections), both of which are small and may not represent viable populations. Its rarity in Minnesota, its general scarcity in the region, and the vulnerability of its habitats are the basis for its state threatened status.

  Description

Carex garberi is a perennial sedge. It produces shoots from a short underground rhizome. Several shoots may be clustered fairly close together, giving a more or less clumped appearance. Leaves and flowering culms may reach approximately 20-30 cm (8-12 in.) in height. Leaves are a few millimeters wide and culms are about 1 mm (0.04 in.) wide. There are several small spikes (flower clusters) on each culm; the terminal spike usually has several to many female flowers at the top (producing perigynia or fruits) and male flowers (stamens) are on the lower portion. Rarely, some culms have only a few perigynia at the top of the terminal spike. These specimens can be confused with C. aurea, if they are collected after the perigynia of C. aurea lose their distinctive golden-orange color. Perigynia of C. garberi are white and have a granular appearance with magnification. It is important to note the fresh color of mature specimens in the field and to carefully examine the population for the typical form of the terminal spikelet.

Technical Description: Culms loosely cespitose, 5--25 cm (2—10 in.) long. Rhizomes slender, to about 10 cm (4 in.) long. Leaves to 2.5 mm (0.1 in.) wide. Terminal spike entirely pistillate or staminate at base, rarely entirely staminate, 5--14 mm (0.2—0.6 in.) long, peduncled. Lateral spikes pistillate, 1--3 per culm, 5--18 mm (0.2—0.7 in.) long, peduncled; perigynia evenly and ± closely arranged on the rachis with the middle internodes 0.2--0.7 mm (0.008—0.028 in.) long, the lower internodes similar. Pistillate scales with greenish midrib and yellowish brown or reddish brown flanks, blunt to acute or short-mucronate, ascending or appressed. Perigynia glabrous, 5--24 per spike, dull white, broadly ellipsoid, 1.6--2.6 mm (0.06—0.10 in.) long, 1--1.6 mm (0.04—0.06 in.) wide, faintly or strongly veined; apex rounded, beakless. Achenes biconvex, ± circular, 1.4--1.8 mm (0.06—0.07 in.) long; style deciduous. Maturing late May through August.

  Habitat

Because of the very few records of C. garberi in Minnesota, it is not entirely clear which habitats are preferred. The Kittson County wetland site is an extensive rich fen (peatland) complex in an area dominated by C. lasiocarpa ssp. americana (fen wiregrass sedge) and C. buxbaumii (Buxbaum's sedge). Associated plants included Calamagrostis spp. (reedgrass species) and Cladium mariscoides (twig rush) on a peat mat about 0.5 m (20 in.) thick. Within this rich fen complex, C. garberi was localized in patches of sparser vegetation, where the surface was encrusted with whitish deposits of calcium carbonate. The other records of C. garberi in Minnesota are from transitional or successional wetlands that developed following gross human disturbance of the substrate, which seem to have created favorable, if short-lived, conditions. Favored substrates appear to be moist or seasonally wet, non-acidic, sparsely vegetated, and exposed to direct sunlight.

  Biology / Life History

Carex garberi is a short-lived perennial that produces leafy shoots in the spring from belowground rhizomes; fertile culms arise in June. This species, like all or most sedges, is wind-pollinated. Fertilized female flowers produce mature fruit rapidly in June and July. How the fruits are dispersed is unknown. However, the fruit (perigynia) are white in color and conspicuously displayed in the spike, indicating they may be attractive to seed foraging birds or mammals.

  Conservation / Management

The rich fen complex in Kittson County where C. garberi has been found occurs on a state Wildlife Management Area and is protected from commercial or agricultural development. But the wetland is not immune to hydrologic alterations related to nearby agricultural activities, road and ditch maintenance, or wildlife management. A commitment to maintaining the hydrologic regime of this wetland is critical.

  Best Time to Search

The best time to search for Carex garberi is when it is in fruit from late June to early August. Full-grown fruits are necessary for positive identification.

  Conservation Efforts in Minnesota

The Kittson County site is on land that is protected from development, though the management needs of C. garberi have not been specifically addressed.

  Authors/Revisions

Welby R. Smith (MNDNR), 2021

(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.

Brumback, W. E. 2001. New England plant conservation program conservation and research plan: Carex garberi Fern. (Garber's Sedge or Elk Sedge) and Triantha glutinosa (Michx.) Baker (Sticky False Asphodel). New England Wild Flower Society, Framingham, Massachusetts. ii + 43 pp.

Smith, W. R. 2018. Sedges and rushes of Minnesota: the complete guide to species identification. University of Minnesota Press, Minneapolis. 696 pp.