Rare Species Guide

  Basis for Listing

Carex jamesii (James’ sedge) is found in several central and eastern states, reaching the northwestern limit of range in Minnesota where it is nearly restricted to The Blufflands region in the southeastern part of the state. Even within seemingly ideal habitat, this species is extremely rare. The Minnesota Biological Survey located only a few sites supporting C. jamesii. Threats to this species include the reduction in canopy cover and soil disturbances that typically accompany timber harvest, increased erosion on slopes, invasion of non-native species, livestock grazing, and construction activities, particularly building roads, trails, and homes. Given its extreme rarity and the perceived threats, C. jamesii was listed as a threatened species in Minnesota in 1996. 

  Description

Sedges are grass-like perennial herbs that can be easily identified to the genus Carex by their 3-ranked leaves, closed sheaths and triangular (only occasionally round), mostly solid stems with a terminal inflorescence. However, identifying a sedge to species is often difficult, and positive identification usually requires mature perigynia (the structure that appears to be the seed or fruit but is actually a bract enclosing the ovary) to be present. The fruit enclosed by the perigynium is an achene. 

Carex jamesii is a smallish sedge with slender tufted stems and leaves that tend to arch over. The stems are much shorter than, and somewhat hidden within, the leaves. Each spike usually has only 2 or 3 pistillate (female) flowers, each with an exceptionally long green scale at its base. The staminate (male) flowers are clustered on an inconspicuous terminal spike and have very short scales. The body of the perigynium is nearly spherical with a long slender sharply angled beak, which constitutes ? - ½ the length of the perigynium. Bases of leaves and culms are brown or greenish (compared to maroon/purple in similar species).

Technical Description: Culms cespitose, to 100 cm (39 in.) long, wing-margined, weak, appearing flat in pressed specimens. Rhizomes to about 3.0 cm (1.2 in.) long. Leaves to 7 mm (0.3 in.) wide; ventral surface of sheaths smooth, not wrinkled, not spotted with colored dots, thickened at summit with a narrow horizontal band of hardened tissue (sometimes yellowish tinged); basal sheaths disintegrating into pale brown fibers; ligules longer than wide. Inflorescence 2--6 cm (0.8—2.4 in.) long; compound, with a few to several short side branches, especially in lower portion of inflorescence. Spikes numerous, sessile, androgynous; bracts setaceous. Pistillate scales about half the length of the perigynia. Perigynia glabrous, lanceolate, 4.5--6 mm (0.18—0.24 in.) long, 1.3--2 mm (0.05—0.08 in.) wide; dorsal surface with distinct continuous veins; ventral surface similar or with only faint or discontinuous veins; base spongy or pulpy, often distended or bulbous at maturity; apex tapered or gradually contracted to an indistinct bidentate serrulate beak 2--3 mm (0.08—0.12 in.) long; beak as long or longer than the body. Achenes biconvex; style deciduous. Maturing early June to early July.

  Habitat

In general, C. jamesii occurs in rich woods, especially in calcareous soil. In Minnesota specifically, it is found on steep north- to east-facing slopes and narrow stream bottomlands in closed-canopy forests of Acer saccharum (sugar maple) and Tilia americana (basswood). Except in the richest settings, populations on slopes are generally restricted to the lower slope. Population size is often small but may range up to several hundred individuals in one location.

  Biology / Life History

Carex jamesii is a low, densely tufted species that sends up fertile culms in mid-spring. Culms are short and few in number compared to the dense tuft of narrow leaves that often obscures the culms. Once perigynia are shed, usually in July, the leaves grow through the summer but are nearly indistinguishable from other narrow-leaved, brown-based woodland sedges. As is the case with all or most sedges, the flowers of C. jamesii are wind-pollinated. Seed dispersal mechanisms are unknown.

  Conservation / Management

Because of this species' low numbers and restricted habitat in The Blufflands region, its future depends on conscientious land managers in the southeastern part of the state. All small colonies that have been located to date occur on steep slopes in densely forested areas. Any significant removal of trees will change the habitat by allowing more solar energy to reach the forest floor, which will in turn dry and warm the soil. These changes will make the habitat unsuitable for C. jamesii and a number of other sensitive plant species. Other threats include livestock grazing, which can lead to erosion, trampling, and introduction of harmful non-native species. Road building and residential development pose additional challenges to protecting this rare sedge.

  Best Time to Search

The best time to search for Carex jamesii is during its fruiting period from late May through June.

  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.

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.

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.