Carex davisii (Davis' Sedge)

Plant Info
Also known as:
Genus:Carex
Family:Cyperaceae (Sedge)
Life cycle:perennial
Origin:native
Status:
  • State Threatened
Habitat:part shade, shade; floodplain forest
Fruiting season:June - August
Plant height:12 to 36 inches
Wetland Indicator Status:GP: FAC MW: FAC NCNE: FAC
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 spikes] A single staminate spike up to 1½ inches long at the top of the stem, which almost always has a few to several pistillate flowers at the tip (gynecandrous) and occasionally has a few more staminate flowers above that (androgynecandrous). Below this terminal spike are 2 to 4 slender-stalked spikes that are almost always all-pistillate. Lateral spikes are widely spaced, though the uppermost 1 or 2 may overlap the terminal spike. The stalk of the lowest spike is up to 1 inch long with stalks becoming progressively shorter as they ascend the stem, initially erect to ascending, often becoming nodding with maturity. At the base of each lateral spike is a leaf-like bract that often over-tops the terminal spike.

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

[photo of sheath and ligule] Leaves are basal and alternate, 3 to 8 mm wide, longer or shorter than the flowering stems, becoming arching. Stem leaf sheaths loosely wrap the stem and are translucent greenish to light brown on the front, often red-dotted. The ligule (membrane where the leaf joins the sheath) is about as long as wide. Leaves are M-shaped in cross-section, mostly hairless on the upper surface, the underside and edges variously covered in short, white hairs which continue down the back of the sheath.

[photo of purple tinging at the base] Bases are wrapped in a sheath that is hairy, not fibrous, and typically tinged red to purple, turning brown as they wither with age. Stems are 3-sided, smooth or hairy along the angles, erect to ascending, elongating to as much as 36 inches at maturity, longer or shorter than the leaves. Not all plants produce flowering stems. Plants form loose to dense clumps and are not colony-forming.

Fruit: Fruit type: seed without plume

[photo of maturing spike] 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. Pistillate spikes each contain 10 to 40 fruits that are erect to ascending and overlapping on the stalk.

[photo of perigynia, scale and achene] Pistillate scales are egg-shaped, translucent white tinged brown with a green midrib that turns brown, the midrib extending to an awn up to 3 mm long, the scale body much shorter than the perigynia but the awn often extending beyond the perigynia. Perigynia are green turning dull orange at maturity, 4.5 to 6 mm long, 2 to 2.5 mm wide, 2-ribbed with 9 to 12 distinct veins, hairless, loosely wrapping the achene, oval to egg-shaped, abruptly tapering at the tip to a short, obscurely toothed beak. Achenes are 2.2 to 2.7 mm long, up to 1.2 mm wide, 3-sided in cross-section, and mature to dark brown.

Notes:

Carex davisii is found in river bottoms and floodplain forest and reaches the northern edge of its range in southern Minnesota. According to the DNR, much of the natural floodplain associated with major rivers has been lost or degraded largely due to human intervention. Besides the lock and dam system on the Mississippi River disrupting natural water level cycles, development of various sorts as well as agriculture has destroyed much of the forest cover, and invasive species round out the list of threats. Carex davisii was listed as a state Threatened species in 1984.

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 davisii is in the Hymenochlaenae section; some of its common traits are: typically clump forming and forming loose colonies, leaves M-shaped in cross-section when young, spikes long and cylindric and drooping on slender stalks, terminal spike either all staminate or with a few perigynia (usually at the tip, occasionally the base), perigynia round in cross-section, 2-veined, beaked, the beak usually toothed, 3-sided achenes, often growing in woodlands.

Carex davisii is distinguished from other sedges in Minnesota by the combination of: hairy leaves and sheaths, reddish basal sheaths (though age to brown), terminal spike staminate at the base with several perigynia at the tip, lateral spikes almost always all pistillate, pistillate scales awned, the scale body much shorter than the perigynia but the awn often extending beyond it. It is most similar in appearance to another hairy Minnesota sedge: the also-rare Carex formosa, which has pistillate scales that are merely pointed or short-awned and consistently shorter than the perigynia, and its lateral spikes almost always have 1 or 2 staminate flowers at the base.

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More photos

Photos by K. Chayka and Peter M. Dziuk taken in the garden. Photos courtesy Brian O'Brien taken in Waseca County.

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