Carex echinodes (Marsh Straw Sedge)

Plant Info
Also known as: Pointed Quill Sedge
Genus:Carex
Family:Cyperaceae (Sedge)
Life cycle:perennial
Origin:native
Habitat:part shade, shade, sun; wet to dry soil; deciduous forest, floodplains, wooded slopes, wooded bluffs, river banks, swamp and bog edges
Fruiting season:June - July
Plant height:12 to 36 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 spike clusters] 3 to 8 spikes each 4 to 14 mm (to ~½ inch) long, all at the tip of the stem but not crowded, the upper spikes commonly loosely overlapping and the lower more widely separated, the inflorescence (group of spikes) up to about 2 inches long and typically nodding or arching. All spikes are stalkless, erect to ascending, rounded at the tip, rounded to tapered at the base and club-shaped to oval to nearly round in outline, with staminate (male) flowers at the base and pistillate (female) flowers at the tip (gynecandrous). At the base of the lowest spike is a scale-like bract with a bristle-like tip that may be longer than the spike and sometimes overtops the terminal spike.

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

[photo of sheath and ligule] Leaves are alternate with 3 to 5 leaves on the lower third of the stem, up to 13 inches long, 1.5 to 3 mm wide, flat, hairless, smooth or rough along the edges and midvein, and shorter than the flowering stems. Stem leaf sheaths tightly wrap the stem, are green or green and white mottled on the front with a Y-shaped, whitish translucent area up to 4 inches long at the tip that does not extend much above the leaf base and is straight to U-shaped across the top edge. The lower sheaths may have whitish cross-partitions between the veins. The ligule (membrane where the leaf joins the sheath) is as long as or longer than wide. Bases are wrapped in a pale brown to dark purple-brown sheath that may be somewhat fibrous, with old sheaths often persisting to the next season. Stems are hairless, erect to ascending, 3-sided in cross-section, very slender, mostly smooth except just below the spikes. Stems may elongate to 36 inches at maturity and are longer than most leaves. Plants are clump forming from a mix of flowering and vegetative shoots, the vegetative stems with 6 to 10 leaves mostly clustered near the tip.

Fruit: Fruit type: seed_without_plume

[close-up of mature spikes] Fruit develops in late spring to early summer, the spikes forming clusters of seeds (achenes), each wrapped in a casing (perigynium), subtended by a scale. Perigynia are ascending to widely spreading, the perigynia tips sometimes recurved (curved back). Each spike contains 10 to 30 fruits.

[photo of perigynia scale and achene] Pistillate scales are lance-oblong, translucent yellowish to brown-tinged with a green or brown midrib, blunt to pointed at the tip, narrower than and 60% to 85% as long as the perigynia. Perigynia are 3.2 to 4.6 mm long, 1.3 to 2.1 mm wide, greenish to golden-brown at maturity, hairless, 5 to 7-veined on the front, 2 to 6-veined on the back (may be faint), flattened, not inflated, the body elliptic to narrowly egg-shaped, widest just above the base, tapered to a beak 1 to 1.5 mm long, and has a thin, papery wing .1 to .45 mm wide around the edges that extends to the base but may be obscure until the perigynia dries down. Achenes are lens-shaped, brown at maturity, 1.4 to 1.7 mm long, .8 to 1.1 mm wide, elliptic to narrowly egg-shaped; the distance from the tip of the achene to the tip of the beak is 1.4 to 2.4 mm.

Notes:

Carex echinodes is a fairly common sedge throughout much of the state, found in deciduous forests, floodplains, swamp and bog edges, and the margins of rivers, lakes and ponds, usually in moist, shady places, less often in drier or sunny spots.

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 echinodes is a member of the Ovales section, a notoriously difficult group. Some common traits are: usually clump forming, basal sheaths brown and somewhat fibrous, leaves V-shaped when young; 2 to 20 stalkless spikes all at the stem tip and crowded or not, spikes usually all pistillate at the tip and staminate at the base (gynecandrous), lowest bracts scale-like usually with a bristle tip, pistillate scales blunt to pointed at the tip and sometimes awned; perigynia erect to spreading, hairless, veinless to conspicuously veined on one or both surfaces, flat, beaked, usually with a translucent, papery wing; achenes lens-shaped.

Some traits to look at in Ovales are whether spikes are all crowded at the tip or more loosely arranged, whether the inflorescence is nodding or mostly erect, the shape of the spike (round vs. elliptic vs. club-shaped), the size and shape of the perigynia particularly the body (e.g. round vs. elliptic), the width of the wing and whether it extends all the way to the base, whether there are distinct veins on one or both sides of the perigynia, the length of the pistillate scale relative to the perigynia, the shape of the achene, leaf width, and whether sheaths are papillose, but strong magnification (30x or more) is required to see this. Habitat can also be a factor, and a metric scale is essential since fractions of millimeters make a difference.

Carex echinodes is distinguished from other Minnesota Ovales species by widest leaves less than 3 mm wide, tight sheaths, the lower sheaths usually with pale cross-partitions between the veins; 4 to 8 spikes in a nodding or arching inflorescence, the lower spikes may be more separated than the upper, spikes rounded at the tip and mostly tapered at the base, lowest perigynia on a spike ascending to spreading; pistillate scales 60% to 85% as long as the perigynia; perigynia 3.2 to 4.6 mm long, the body elliptic to egg-shaped, veined on both sides (sometimes faintly), the wing .1 to .45 mm wide extending all the way to the base. The distance from the tip of the achene to the tip of the beak is 1.4 to 2.4 mm. It is usually found in moist to wet soil, often in shade or part shade.

Carex echinodes can be very difficult to distinguish from C. tenera; until recently they were considered varieties of the same species (C. tenera var. echinodes and var. tenera) and share many of the same traits. The pistillate scales of C. tenera are longer (80% to 100% as long as the perigynia), its sheaths are usually papillose at least near the tip, though it may be sparse and requires strong magnification to see, its perigynia tend to be proportionately broader with a shorter beak and are not as widely spreading on the spike. Also very similar is C. normalis, which has widest leaves usually more than 3 mm, sheaths with more numerous and obvious cross-partitions, usually a straighter, stiffer and more compact inflorescence, spikes are more rounded at the base with few staminate flowers.

The nodding inflorescence is similar to several other members of Ovales, in particular C. projectaC. foenea and C. scoparia, which may have more than 8 spikes, widest leaves more than 3 mm, loose sheaths, longer perigynia or longer scales.

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More photos

Photos by Peter M. Dziuk taken in Fillmore and Rice counties, and in Wisconsin.

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