Rare Species Guide

  Basis for Listing

The range of this distinctive forest species is geographically centered in the eastern Great Lakes region. Minnesota appears to be at the extreme western periphery of its range. Carex plantaginea (plantain-leaved sedge) appears to be common only in the center of its range and becomes increasingly sporadic and uncommon south and west of that area. Based on collection records, C. plantaginea seems to be very rare in southeastern Minnesota. Because of its broad evergreen leaves, it would be difficult to overlook this plant in the field or mistake it for another species. The fact that there are only four records probably reflects its true rarity in the state. Two records, one in Hennepin County and the other in Winona County, represent populations not seen in over 100 years. It is generally assumed that they were extirpated by urban development. The other two records, one in Wabasha County and one in Winona County (both in The Blufflands Subsection), have been seen more recently and are believed to survive as of 2020 Another measure of its suspected decline is the well-documented loss of its habitat in maple-basswood forests in east-central and southeastern Minnesota due to agriculture, residential, recreational, and commercial development. Given its rarity in the state and the threats to its habitat, C. plantaginea was listed as an endangered species in Minnesota in 1996.

  Description

There are several distinctive features of C. plantaginea, but the broad leaves are the attention-getter. Minnesota has only three Carex species with such broad leaves: C. plantaginea, C. careyana (Carey’s sedge) and C. albursina (white bear sedge). In the case of C. plantaginea and C. careyana, the bases of the leaves are distinctly reddish, those of C. albursina are essentially green. In order to distinguish C. plantaginea from C. careyana, check the bract at the base of each pistillate spike. In the case of C. plantaginea, the bracts are predominately reddish and each has a short pointed projection at the top, which is the rudimentary blade. The bracts of C. careyana are entirely green or they may have a small band of red at the base of the sheaths, and the bracts of C. careyana have recognizable blades, especially bracts of the lower spikes. 

Technical description: Culms cespitose, to 55 cm long, erect, gone by mid-summer. Rhizomes stout, to 1 cm long or not apparent. Leaves basal, to 40 cm long and 3 cm wide, shorter than the culms; sheaths red or red-brown. Bracts bladeless or with rudimentary blades to 1.5 cm long; sheaths 2--4 cm long, partially or predominately red or red-brown. Terminal spike staminate, 1--2 cm long; peduncle 1--4.5 cm long. Lateral spikes pistillate, 2--5 per culm, erect, widely spaced, 1--2.8 cm long; peduncles contained within bract sheaths. Pistillate scales somewhat shorter than the perigynia, awned. Perigynia elliptic, 3.6--5 mm long, 1.6--2 mm wide, with 7--13 veins per side, contracted or tapered to a slightly askew beak, narrowed to the base. Achenes trigonous, ovate to elliptic, 2.2--2.7 mm long; style deciduous. Maturing early May to late June (Smith 2018).

  Habitat

In Minnesota, C. plantaginea occurs in moist, shaded hardwood forests in the southeastern corner of the state. Within such forests, it appears to favor north-facing slopes, steep ravines, or other cool, protected microhabitats. Acer saccharum (sugar maple) and Tilia americana (basswood) are often the dominant canopy trees. Populations of C. plantaginea may range from only a few individuals to 100 or more.

  Biology / Life History

Carex plantaginea is a perennial species active throughout the growing season, but in some ways it acts almost like a spring ephemeral, sending up its leafless fertile stems early in the spring before the leaves of the canopy trees appear. These stems continue to elongate throughout May and early June, eventually fall over onto the forest floor, and disappear by mid-summer. This may be a dispersal mechanism for the perigynia. By late spring, when the stems are elongating, the plant sends up a flush of basal leaves that grow through the summer and then overwinter intact or at least partially intact. This life cycle is similar to the other rare wide-leaved forest sedge C. careyana, but different from the common C. albursina, a wide-leaved forest sedge that sends up its fertile stems with the basal leaves in mid- to late spring.

  Conservation / Management

Agricultural, residential, and commercial development in southeastern Minnesota has reduced the extent of the original habitat of C. plantaginea to small scattered remnants. These remnants are often further degraded by livestock grazing, which results in direct loss of plants, soil compaction, trampling, and the introduction of non-native invasive species. The habitat can also be degraded by certain human activities that open significant gaps in the canopy. When this happens, the increased solar radiation causes the soil to become warmer and dryer, which will drastically alter the soil biota and shift the competitive balance from native mesic forest species to more aggressive invasive species that are better adapted to the altered conditions. Another concern is soil erosion caused by heavy machinery that might be used upslope of known populations. Unless invasive species are present, the habitat of C. plantaginea will need no active management to sustain itself. A suitable buffer should be established within which only minimal activity should be allowed.

  Best Time to Search

The best time to search for Carex plantaginea is May to early July when fertile culms are present. The broad evergreen leaves with their maroon bases can be found throughout the year.

  Conservation Efforts in Minnesota

The Minnesota Biological Survey has been completed in the range of this species in the state, providing reliable information about its distribution and abundance.

  Authors/Revisions

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.

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.

Nekola, J. C. 1990. Rare Iowa plant notes from the R. V. Drexler Herbarium. Journal of the Iowa Academy of Science 97(2):55-73.

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