Carex grayi (Gray's Sedge)
|Also known as:||Common Bur Sedge, Morning Star Sedge|
|Habitat:||part shade, shade; moist soil; floodplain forest, shady seeps|
|Fruiting season:||June - July|
|Plant height:||1 to 3 feet|
|Wetland Indicator Status:||GP: FACW MW: FACW NCNE: FACW|
|MN county distribution (click map to enlarge):|
|National distribution (click map to enlarge):|
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Separate staminate (male) and pistillate (female) spikes, with a single staminate spike ¼ to 2½ inches long at the tip of the stem. Below the staminate spike are 1 or 2 erect pistillate spikes, round in outline, 1 to 1½ inches in diameter, on stalks up to 1 3/8 inches long. At the base of each pistillate spike is a leaf-like bract that is 3 to 10 inches long and usually much over-tops the terminal spike. The uppermost pistillate spike is near the staminate spike but does not crowd it; the lower pistillate spike, when present, may be more widely separated from the one above it.
Leaves and stems:
Leaves are basal and alternate, mostly near the base, 4 to 11 mm wide, 5 to 12 inches long; the upper stem leaves may over-top the terminal spike. Stem leaf sheaths are U-shaped at the tip, papery whitish-green, and loosely wrap the stem. The ligule (membrane where the leaf joins the sheath) is mostly longer than wide, rounded to pointed at the tip. Leaves are hairless.
Bases are wrapped in a sheath that is purplish-red and not fibrous. Stems are erect, stout, 3-sided in cross-section, and smooth but slightly rough near the flowering spikes. Stems elongate up to 3 feet at maturity and are mostly longer than the leaves. Not all plants produce flowering stems. Plants often grow in clumps, sometimes form small colonies from short rhizomes.
Fruit develops in late spring to mid-summer, the pistillate spikes forming clusters of seeds (achenes), each wrapped in a casing (perigynium), subtended by a scale. Perigynia are tightly crowded on the spike, radiating in all directions from the short central stalk, forming a sphere. Each pistillate spike contains 8 to 35 fruits.
Pistillate scales are lance to egg-shaped to nearly round, pale brown with a green midrib, pointed at the tip or the midrib extending to an awn up to 7mm long, shorter and narrower than the perigynia and may be hidden by it. Perigynia are 12.5 to 20 mm long, 4 to 8 mm wide, green at maturity, hairless or rarely minutely hairy, strongly 16 to 25-veined, generally flask-shaped with a long taper to a straight beak that has 2 somewhat spreading teeth at the tip. Achenes are 3-sided, 3.3 to 4.8 mm long, 2.6 to 3.7 mm wide, maturing to brown, with a long, persistent, contorted style that typically withers with age.
Carex grayi is an uncommon sedge of floodplain forests, primarily along the Mississippi River and its major tributaries, and reaches the northwest limit of its range in southern Mille Lacs County. According to the DNR, it's dependent on seasonal flooding as a means of seed dispersal but the lock and dam system for controlling water levels on the Mississippi disrupt the natural cycles and limits this species' ability to go forth and prosper. It was consequently listed as a Special Concern species in 2013.
Carex is a large genus, with over 600 species in North America and 150+ in Minnesota alone. They are grouped into sections, the species in each group having common traits. Carex grayi is in the Lupulinae section; some of its common traits are: clump forming or not, rhizomatous but rarely forming colonies, hairless leaves, basal sheaths usually red-purple and not fibrous, sheaths and larger leaves with cross partitions between veins (septate-nodulose), 2 to 9 spikes, terminal spike all-staminate, lateral spikes stalked, erect to ascending, round to thick cylindrical, all-pistillate or with a few staminate flowers at the tip (androgynous), leaf-like bract subtending the lowest pistillate spike, perigynia ascending to spreading, hairless, strongly veined, inflated, mostly teardrop to flask-shaped with a long taper to a toothed beaked, achenes 3-sided in cross-section with a long, persistent style. Species in this section have the largest perigynia of all Carex.
Carex grayi is distinguished from all other Minnesota sedges by the 1 to 1½ inch, globular pistillate spikes with 8 to 35 large, inflated perigynia that are tightly packed and radiating in all directions from a central point, resembling a mace (the medieval weapon). By contrast, other members of the Lupulinae section have thick cylindric pistillate spikes, those of Carex intumescens more loosely arranged with usually 12 or fewer perigynia per spike, and those of Carex lupulina with as many as 80 perigynia per spike, all ascending. While a number of references note the perigynia of C. grayi may be minutely hairy (especially in plants from the Midwest, according to Flora of North America), we did not observe any hairs on any of our specimens. It is apparently a trait that does not have a well-defined distribution.
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Photos courtesy Peter M. Dziuk taken in Winona County. Other photos courtesy Steve Eggers.
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