Carex albursina (White Bear Sedge)

Plant Info
Also known as: Blunt-scaled Wood Sedge
Genus:Carex
Family:Cyperaceae (Sedge)
Life cycle:perennial
Origin:native
Habitat:part shade, shade; average to moist soil; rich woods, wooded bluffs, wooded slopes, ravines
Fruiting season:May - July
Plant height:6 to 24 inches
Wetland Indicator Status:none
MN county distribution (click map to enlarge):Minnesota county distribution map
National distribution (click map to enlarge):National distribution map

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Detailed Information

Spikes: Flower shape: indistinct Cluster type: spike

[photo of flowering spikes] Separate staminate (male) and pistillate (female) spikes, with a single staminate spike up to about ¾ inch long at the top of the stem. Below the staminate spike are 3 or 4 cylindric, erect to ascending, all-pistillate spikes each ½ to 1¼ inches long, the uppermost 1 or 2 stalkless or short-stalked, typically crowding the staminate spike and often over-topping it. Lower pistillate spikes arise singly from the nodes on the upper half of the stem, on erect stalks up to 2¼ inches long. Pistillate spikes each have a leaf-like bract at the base of the stalk that usually over-tops the terminal spike and is much wider than the spikes, concealing them, the widest up to 8.3 mm (1/3 inch) wide. The uppermost bract is often shorter and narrower than the lower bracts.

Leaves and stems: Leaf attachment: alternate Leaf attachment: basal Leaf type: simple

[photo of sheath and ligule (stem removed)] Leaves are basal and alternate, 4 to 14 inches long, 10 to 38 mm (3/8 to 1½ inches) wide, erect to ascending, and shorter than the flowering stem. Stem leaf sheaths loosely wrap the stem and are papery, translucent whitish. The ligule (membrane where the leaf joins the sheath) is longer than wide. Leaves are thin, hairless, M-shaped in cross-section when young, have a prominent midrib and 2 conspicuous lateral veins, and are light green especially near the base.

[photo of plant base] Bases are wrapped in a whitish sheath that is not fibrous. Stems are somewhat spongy, 3-sided and winged along the angles, hairless but rough in the upper plant, erect to ascending to sprawling, and may elongate up to 24 inches at maturity. Not all plants produce flowering stems. Plants typically form dense clumps.

Fruit: Fruit type: seed without plume

[close-up of maturing fruit] Fruit develops in spring through early summer, the pistillate spikes forming clusters of seeds (achenes), each wrapped in a casing (perigynium), subtended by a scale. Staminate scales are white with a prominent green midrib and mostly rounded at the tip. Pistillate spikes have 3 to 20 fruits, the perigynia erect to ascending, overlapping but often loosely arranged on the spike.

[photo of perigynia, scale and achene] Pistillate scales are oblong or broadest at the tip, white with a green midrib, rounded to straight across at the tip, sometimes with a minute point at the apex (mucronate), and about half as long as the perigynia. Perigynia are green to yellowish at maturity, 3 to 4.2 mm long, 1.8 to 2.1 mm wide, 2 ribbed and many-veined (best seen when dry), hairless, not much inflated, asymmetrically urn-shaped, tapering to a spongy base, and with an abrupt taper to a short, toothless, bent beak that is a bit off-center. Achenes are 2.5 to 3.8 mm long, weakly 3-sided in cross-section, oval-elliptic in outline.

Notes:

Carex albursina is a sedge of rich woods, wooded slopes, bluffs and ravines, and reaches the northwest edge of its range in Minnesota. It is named after White Bear Lake, which crosses Ramsey and Washington counties, where it was discovered in abundance by botanist Edmund P. Sheldon in the 1890s.

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 albursina is in the Laxiflorae section; some of its common traits are: usually densely clump forming, short to long rhizomatous, stems slightly winged along the angles, basal sheaths brown or purple and not fibrous, leaves M-shaped in cross-section when young, leaves hairless, widest leaves 5+ mm, 3 to 6 spikes, terminal spike all staminate, lateral spikes all pistillate, lateral spikes subtended by a long-sheathing leaf-like bract, perigynia hairless, generally urn-shaped and tapering to a spongy base, distinctly 8+ veined and abruptly beaked, achenes 3-sided with 3 stigmas, usually growing in woodlands.

Carex albursina is distinguished from other Carex species by the combination of: broad basal leaves (10 to 38mm wide), whitish at the base, leafy bracts that are wider than the spikes and often conceal them, usually 4 spikes, terminal spike all staminate, the uppermost 1 or 2 pistillate spikes crowding the staminate spike and may over-top it, staminate and pistillate scales both white with a green midrib that are rounded to straight across the tip and not awned, perigynia asymmetrical, widest above the middle, 3 to 4.2 mm long with a short, bent, toothless beak, and weakly 3-sided achenes.

Plants with narrower leaves may resemble several other sedges, but the whitish bases, perigynia with short, bent beaks and white, awnless scales about half as long as the perigynia are helpful distinctions. Plants with broader leaves may resemble some members of the Careyanae section, most of which are distinctly red-purple at the base, except for Carex laxiculmis, which has brown basal sheaths, the uppermost pistillate spikes do not crowd the staminate spike, has nodding lateral spikes on thread-like stalks, perigynia is more strongly veined and pistillate scales more lance-shaped, tapering toward the tip and may be short-awned.

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More photos

Photos courtesy Peter M. Dziuk taken in Fillmore, Goodhue and Winona counties.

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