Carex crawfordii (Crawford's Sedge)

Plant Info
Also known as: Early Fen Sedge
Genus:Carex
Family:Cyperaceae (Sedge)
Life cycle:perennial
Origin:native
Habitat:part shade, sun; moist to wet sandy or gravelly soil; shores, wet ditches, meadows, forest clearings, swamps, marshes, floating mats
Fruiting season:June - August
Plant height:10 to 24 inches
Wetland Indicator Status:GP: OBL MW: FAC NCNE: FACW
MN county distribution (click map to enlarge):Minnesota county distribution map
National distribution (click map to enlarge):National distribution map

Pick an image for a larger view. See the glossary for icon descriptions.

Detailed Information

Spikes: Flower shape: indistinct Cluster type: spike

[photo of flowering spikes] 6 to 20 spikes each 5 to 13 mm (to ½ inch) long, all at the tip of the stem, overlapping and usually crowded, the inflorescence (group of spikes) erect and up to about 1 inch long. All spikes are stalkless, erect to ascending, usually tapering at both ends, oval-elliptic 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 is usually 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 or 4 leaves on the lower third of the stem, up to 8½ inches long, 2 to 4 mm wide (commonly less than 3 mm), flat, hairless, rough-textured near the tip. The uppermost leaves may rise slightly above the flowering stem but are more often shorter or about equal to the stem tip. Stem leaf sheaths tightly wrap the stem and are mostly green nearly to the tip, the whitish translucent tip extends above the leaf base and is U- to V-shaped across the top edge. The ligule (membrane where the leaf joins the sheath) is about as long as or longer than wide.

[photo of plant base] Bases are wrapped in a brown sheath that may be somewhat fibrous, with old leaves often persisting to the next season. Stems are hairless, mostly erect, 3-sided in cross-section, mostly smooth except just below the spikes. Stems are often variable in length and may elongate to about 24 inches at maturity. Plants are typically densely clump forming from a mix of vegetative and flowering stems.

Fruit: Fruit type: seed_without_plume

[close-up of maturing spikes] Fruit develops in late spring to mid summer, the spikes forming clusters of seeds (achenes), each wrapped in a casing (perigynium), subtended by a scale. Perigynia are appressed to ascending and crowded on the spike. Each spike contains numerous fruits.

[photo of perigynia, scale and achene] Pistillate scales are lance to egg-shaped, translucent brown-tinged with a green or pale midrib drying to brown, tapering to a sharply pointed tip, the midrib sometimes extending to a very short awn, 3 to 3.8 mm long, somewhat shorter and narrower than the perigynia. Perigynia are 3 to 4.3 mm long, .8 to 1.2 mm wide, light green to reddish-brown at maturity, hairless, veinless to faintly veined on both sides, flattened, not inflated, the body lance-shaped, tapering at the base, long-tapered to the beak, and has a wing .1 to .2 mm wide around the edges that does not extend to the base and is commonly obscure until the perigynia dries down. Achenes are lens-shaped, brown at maturity, 1.1 to 1.5 mm long, .6 to .8 mm wide, narrowly egg-shaped to oblong-elliptic, longer than wide; the distance from the tip of the achene to the tip of the beak is 2 to 3 mm.

Notes:

Carex crawfordii is an occasional to common sedge in moist to wet open places from the Twin Cities north, most often found in sandy or gravelly shores, moist meadows and wet ditches, less often in forest clearings, the margins of swamps and bogs, and sometimes on floating mats. It is noted as opportunistic, establishing itself in seasonally wet, disturbed soils. We encountered it at the edge of a construction site subject to ponding in spring.

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 crawfordii 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 crawfordii is distinguished from other Minnesota Ovales species by widest leaves usually less than 3 mm; 6 to 20 spikes all crowded together at the stem tip and mostly elliptic in shape, tapered at both ends, the inflorescence up to about 1 inch long; perigynia 3 to 4.3 mm long and not more than 1.2 mm wide, veinless to faintly veined on both sides and not winged to the base, though the wing may be obscure on immature plants. The distance from the tip of the achene to the tip of the beak is 2 to 3 mm. It reaches a max height of about 2 feet and is found in a variety of moist to wet soils. The spikes frequently turn a dark coppery brown late in the season. The relatively short stature compared to other Ovales, spikes all crowded at the tip and narrow width of the perigynia are key to an ID.

Carex crawfordii is most similar to C. scoparia, with which it may grow, and which has larger perigynia (4 to 7 mm long and 1.2 to 2 mm wide) and fruiting stems may reach 40 inches tall. The crowded spikes at the tip is also somewhat similar to C. bebbii, which has rounder spikes, perigynia that are also wider than 1.2 mm, and fruiting stems up to about 3 feet tall.

While researching this species I learned that it and several other North American Ovales have been introduced to Europe and parts of Asia and are becoming invasive there. One report from Belarus determined it was weed seed that came in with cranberry plants imported for cultivation from Wisconsin. If we can't stop transporting plants all over the globe, we should at least take better precautions to ensure non-target species are not stow-aways!

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More photos

Photos by K. Chayka taken in Aitkin, Lake and Ramsey counties, and in her garden. Photos by Peter M. Dziuk taken in Lake and Ramsey counties.

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