Carex echinata (Star Sedge)

Plant Info
Also known as: Little Prickly Sedge, Slender Sedge
Genus:Carex
Family:Cyperaceae (Sedge)
Life cycle:perennial
Origin:native
Habitat:sun; wet sandy or peaty soil; shores, bogs, swamps, fens, wet meadows
Fruiting season:June - July
Plant height:4 to 36 inches
Wetland Indicator Status:GP: OBL MW: OBL NCNE: OBL
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 cluster ½ to 3 inches long at the top of the stem, made up of 3 to 8 small spikes, sometimes tightly crowded at the stem tip, sometimes distinctly separated from each other or the lower spikes more removed than the rest. All spikes are stalkless, the terminal spike with pistillate (female) flowers at the tip and a well-defined staminate (male) portion at the base (gynecandrous). Lateral spikes are 4 to 16 mm (to ~2/3 inch) long, mostly pistillate with few (or no) staminate flowers at the base. At the base of the lowest spike is a scale-like bract with bristle tip that may be longer than the spike but does not overtop the terminal spike.

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

[photo of sheath and ligule] Leaves are alternate with 3 to 6 leaves on the lower third of the stem, up to 16 inches long, .7 to 3.3 mm wide, flat or pleated, hairless, smooth or rough along the edges especially near the tip. Some leaves may initially rise above some flowering stems but most do not. Stem leaf sheaths tightly wrap the stem and are translucent whitish, concave at the tip. The ligule (membrane where the leaf joins the sheath) is more or less as long as wide and rounded or pointed at the tip. A few old, dead leaves may persist to the next season.

[photo of plant base] Bases are wrapped in a brown sheath that is not fibrous. Stems are erect to ascending, slender, 3-sided, rough textured on the upper stem, initially longer or shorter than the leaves but can elongate up to about 3 feet at maturity. Plants are densely clump-forming from a mix of flowering and vegetative stems.

Fruit: Fruit type: seed_without_plume

[close-up of maturing spikes] Fruit develops in late spring through early summer, the pistillate spikes forming clusters of seeds (achenes), each wrapped in a casing (perigynium), subtended by a scale. Pistillate spikes each contain 3 to 32 fruits that are erect to ascending on the upper part of the spike and spreading to reflexed (downward pointing) on the lower part.

[photo of perigynia, scale and achene] Pistillate scales are egg-shaped, translucent white to brown-tinged with a green midrib, usually pointed at the tip, awnless, half to about 2/3 as long as the perigynia. Perigynia are 2.9 to 3.6(4) mm long, .8 to 2.1 mm wide, green turning chestnut to dark brown at maturity, hairless, thickened and spongy at the base, flattened on the back side, 2 to 14-veined on the front, veined or not on the back, narrowly triangular to egg-shaped to oval in outline, mostly widest near the base, gradually tapering at the tip to a beak .9 to 2 mm long that is usually at least half as long as the body and is minutely toothed along the edges. Achenes are 1.3 to 2.1 mm long, .8 to 1.6 mm wide, flattened lens-shaped, usually longer than wide and broadest below the middle, and mature to golden yellow.

Notes:

Carex echinata is a common sedge of wet peaty or sandy soils, as well as the rocky north shore of Lake Superior. In Minnesota it is found from the Twin Cities north and is native to parts of North America, Central America, Europe and Asia.

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 echinata is a member of the Stellulatae section; some of the section's common traits are: clump forming, basal sheaths not fibrous, leaves V-shaped in cross-section when young, usually 2 to 10 spikes per stem, terminal spike staminate or pistillate or with pistillate flowers at the tip (gynecandrous), pistillate scales blunt to pointed at the tip, perigynia widely spreading, hairless, veined at least on one side, spongy at the base, 2 short teeth on the beak, achenes lens-shaped. There are similarities with some members of the Phaestoglochin section, which have spikes with staminate flowers above the pistillate (androgynous).

Carex echinata is a variable species but may be distinguished from other Carex species by: 3 to 8 (commonly 4 to 6) gynecandrous spikes at the tip of the stem, crowded or not, 3 to 30 perigynia per spike, the terminal spike with a well-defined staminate portion and stalkless lateral spikes with few (or no) staminate flowers; perigynia 2.9 to 3.6 mm long, spongy at the base, widest at or near the base, veined on one or both sides, usually with a gradual taper to a beak at least half as long as the body; achenes lens-shaped, as long as or longer than wide. The overall shape of the perigynia is variable, from narrowly triangular to egg-shaped to nearly oval.

The variability of this species is evident in the history of its taxonomy, where it was once separated between Carex angustior and Carex cephalantha, the latter a slightly larger plant than the former with more loosely arranged spikes and larger perigynia with more distinct veins on the back, and a shorter beak. There are currently two recognized subspecies of C. echinata: subsp. phyllomanica, restricted to the Pacific coast, has perigynia up to 4.75 mm long and widest leaves up to 3.3 mm; subsp. echinata, present in the rest of the range, has perigynia rarely more than 3.6 mm long and widest leaves less than 2.8 mm wide. The taxonomy may not be entirely settled yet; Flora of North American notes that in some areas, additional varieties have been suggested, based on particularly small or narrow perigynia and/or the loose vs. tight arrangement of the spikes, but intermediate forms are common across the range so these vars probably don't have merit.

Carex echinata is most likely to be confused with Carex interior, which has 2 to 5 spikes (commonly 3) with fewer perigynia (up to 15), smaller perigynia (not more than 3 mm long) usually with an abrupt taper to a short beak not more than half as long as the body, where C. echinata commonly has 4 to 6 spikes with up to 30 or more perigynia, perigynia are usually at least 3 mm long with a longer, more gradually tapered beak at least half as long as the body. C. echinata is most distinct when perigynia are narrowly triangular with a long beak; when perigynia are more egg-shaped to oval with an apparently shorter beak, the number of spikes per stem and number of perigynia per spike may help ID it, but the beak of C. interior is typically stubbier by comparison. As with most Carex, several plants in a population should be checked for these traits.

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More photos

Photos by K. Chayka taken in Anoka, Cook and Lake counties. Photos by Peter M. Dziuk taken in Cook and Lake counties.

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