Carex bromoides (Brome-like Sedge)

Plant Info
Also known as:
Genus:Carex
Family:Cyperaceae (Sedge)
Life cycle:perennial
Origin:native
Habitat:part shade, shade, sun; moist to wet; floodplain forest, thickets, swamps, marsh edges, swales, woodland ponds
Fruiting season:June - July
Plant height:9 to 36 inches
Wetland Indicator Status:GP: none MW: FACW NCNE: FACW
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] 2 to 7 stalkless spikes, erect to ascending, mostly all essentially alike, the lowest often well separated from the one above by as much as 2/3 inch, the upper spikes more closely crowded and overlapping. The spike at the tip of the stem has 1 to a few staminate (male) flowers at the base and 4 or more pistillate (female) flowers at the tip (gynecandrous); the remaining spikes are usually gynecandrous, occasionally all-pistillate or all-staminate or otherwise mixed. At the base of a lateral spike is an awned, scale-like bract that is usually shorter than the attending spike.

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

[photo of stem sheath and ligule] Leaves are basal and alternate, mostly near the base, 1.3 to 3 mm wide, shorter than the flowering stems, mostly soft and arching with 3 to 5 leaves per stem. Stem leaf sheaths tightly wrap the stem and are translucent whitish, concave to U-shaped at the tip. The ligule (membrane where the leaf joins the sheath) is as long as or longer than wide. Leaves are hairless and smooth, V-shaped in cross-section when young. The remains of leaves persist to the next season.

[photo of basal sheaths] Bases are wrapped in a light brown sheath. Stems are slender, 3-sided, rough textured on the upper stem. Stems often become leaning to nearly prostrate, elongating up to about 3 feet at maturity and are much longer than the leaves. Not all plants produce flowering stems. Plants form dense clumps from short rhizomes, the old stems and leaves forming a tussock over time.

Fruit: Fruit type: seed without plume

[photo of mature 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. Spikes each contain 4 to 19 fruits that are erect to ascending and overlapping but not tightly crowded on the stalk.

[photo of perigynia front and back, scale and achene] Pistillate scales are oblong to narrowly egg-shaped, whitish with a green midrib drying to light brown, either tapering to a pointed tip or the midrib extending to a short awn, minutely serrated along the midrib tip and awn, are shorter and wider than the perigynia with the scale body wrapping around the perigynia body. Perigynia are 3.5 to 6.7 mm long, .8 to 1.3 mm wide, 4 to 6 times as long as wide, greenish to golden brown at maturity, distinctly 4 to 8-veined on the outer (front) surface, 3 to 6-veined on the inner (back) surface, hairless but with minute serrations along the tip edges, tightly wrapping the achene at the top of the body but pale and spongy in the lower half, narrowly lance-elliptic, widest near the middle with a long taper to the slender beak that has 2 teeth at the tip. Achenes are 1.7 to 2.2 mm long, .7 to 1.1 mm wide, 2 to 3 times as long as wide, flattened lens-shaped, and mature to brown.

Notes:

Carex bromoides reaches the western edge of its range Minnesota, found primarily in forested swamps, seeps and floodplains in our east-central counties north of the Metro area.

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 bromoides is in the Deweyanae section; some of its common traits are: growing in dense to loose clumps, basal sheaths brown and usually fibrous, leaves flat or V-shaped in cross-section when young, leaves hairless and smooth, 3 to 9 stalkless spikes, terminal spike usually with staminate flowers at the base (gynecandrous), lateral spikes gynecandrous or all-pistillate, perigynia flattened in cross-section and spongy at the base, perigynia erect to ascending with a tapering beak, the beak obscurely toothed if at all, flattened lens-shaped achenes.

Carex bromoides is a fairly distinctive species, distinguished by the combination of: clump forming and tussock forming, widest leaves 3mm wide or less, most or all spikes with a few staminate flowers at the base (gynecandrous), the perigynia distinctly nerved and very slender, usually not over 1mm wide. The only other member of the Deweyanae section in Minnesota is Carex deweyana, which has more obscurely veined and proportionately broader perigynia, 1.3mm wide or more, as well as wider leaves, to 4.2mm wide. There are 2 subspecies of C. bromoides: subsp. bromoides, described above and found in the eastern half of North America, and subsp. montana, found in the Blue Ridge Mountains region of the Carolinas and Virginia.

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More photos

Photos courtesy Peter M. Dziuk taken in Pine County.

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