Carex canescens (Silvery Sedge)
|Also known as:||White Sedge|
|Habitat:||part shade, sun; bogs, conifer swamps, alter thickets|
|Fruiting season:||June - August|
|Plant height:||10 to 30 inches|
|Wetland Indicator Status:||GP: OBL MW: OBL NCNE: OBL|
|MN county distribution (click map to enlarge):|
|National distribution (click map to enlarge):|
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4 to 8 oval-elliptic to short-cylindric spikes, each up to ½ inch long, usually the lower spikes more widely separated than the upper with the uppermost spikes not overlapping or crowded. At the base of the lowest spike is a narrow, bristle-like bract, rather longer than the spike but much shorter than the inflorescence (group of spikes). All spikes have staminate (male) flowers at the base and pistillate (female) flowers at the tip (gynecandrous); the terminal spike at the tip of the stem is nearly half staminate while the lateral spikes are mostly pistillate with just a few staminate flowers. It is not uncommon for the stem to angle at one of the spikes, nodding from that point.
Leaves and stems:
Leaves are basal and alternate, mostly near the base, 2 to 4 mm wide, usually shorter than the flowering stems, mostly floppy. The remains of the previous season's leaves typically persist in a tan rosette around the base. Stem leaf sheaths tightly wrap the stem and are translucent whitish, typically U-shaped at the tip. The ligule (membrane where the leaf joins the sheath) is longer than wide. Leaves are hairless and flat, though V-shaped in cross-section when young and may be rough around the edges, especially near the tip. Color is pale green to gray-green or blue-green.
Bases are wrapped in a brown sheath that is not fibrous. Stems are slender, 3-sided and rough textured near the flowering spikes. Stems are mostly erect, elongating up to 3 feet at maturity and mostly longer than the leaves. Not all plants produce flowering stems. Plants form dense clumps and may form loose colonies from short rhizomes.
Fruit develops in late spring through mid-summer, the pistillate spikes forming clusters of seeds (achenes), each wrapped in a casing (perigynium), subtended by a scale. The empty staminate scales persist after fruit has dropped off. Pistillate spikes each contain 10 to 30 fruits that are appressed, ascending or spreading and not tightly crowded on the stalk.
Pistillate scales are generally egg-shaped, translucent white later tinged brown, with a green midrib, blunt or pointed at the tip, and narrower and a little shorter than the perigynia. Perigynia are 1.8 to 3 mm long, 1.2 to 1.7 mm wide, with several light veins that are more visible on the outer face, hairless, tightly wrapping the achene but spongy at the base, oval-elliptic, widest near the middle, a short taper to the beak with minute teeth along the edge, 2 minute teeth at the tip of the beak, gray-green to blue-green when young becoming yellowish brown at maturity. Achenes are 1.25 to 1.5 mm long, up to 1.25 mm wide, flattened lens-shaped, and mature to light brown.
Carex canescens is found in Minnesota from the Metro north, primarily in bogs and swamps as well as the rocky north shore of Lake Superior.
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 canescens is in the Glareosae section; some of its common traits are: typically clump forming, leaves V-shaped in cross-section when young, leaves hairless and 4mm or less wide, 2 to 10 stalkless spikes, spikes all essentially alike with staminate flowers at the base (gynecandrous), perigynia ascending to spreading and flattened in cross-section, beaked, the beak usually toothed, flattened lens-shaped achenes, typically growing in wetlands.
Carex canescens is distinguished by leaves to 4 mm wide, spikes with 10 to 30 perigynia, the spikes not typically all crowded at the tip, and a waxy bloom giving the perigynia and leaves a somewhat silvery to blue-green cast especially when young. Most similar is Carex brunnescens, which has leaves only up to 2.5 mm wide, 5 to 10 perigynia per spike, perigynia with a longer beak and a distinct slit on the outer face. There are 2 recognized subspecies of C. canescens, both of which have been found in Minnesota, though many herbarium records are not identified to the subspecies level: subsp. canescens is presumed the more common of the two, has flowering stems up to 2 feet long and the inflorescence rarely exceeds 2 inches long, with more congested spikes, the lowest spike not more than ¾ inch from the one above it; subsp. disjuncta has flowering stems to 3 feet long and an inflorescence to 4½ inches (or longer), the spikes more separated with the lowest spike as much as 2 inches from the one above it.
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Photos by K. Chayka taken in Cook County. Photos courtesy Peter M. Dziuk taken in Cook and Lake counties.
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