Scirpus pendulus (Rufous Bulrush)
|Also known as:||Nodding Bulrush, Red Bulrush|
|Habitat:||sun; wet; shores, swamps, wet ditches, wet meadows|
|Fruiting season:||June - August|
|Plant height:||2 to 4 feet|
|Wetland Indicator Status:||GP: OBL MW: OBL NCNE: OBL|
|MN county distribution (click map to enlarge):|
|National distribution (click map to enlarge):|
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Open, nodding, branching cluster at the top of the stem, often with a smaller cluster arising from the uppermost leaf axil. Spikelets (flower clusters) are numerous, all single and mostly on slender stalks, some stalkless. Spikelets are 5 to 10 mm long (to ~3/8 inch), lance-elliptic to cylindric, blunt at the tip, brown to reddish-brown, with florets spirally arranged. Florets are perfect (both male and female parts) each with a 3-parted style and subtended by a single scale.
At the base of the cluster, surrounding each of the lowest main branches, are leaf-like bracts with sheaths that are usually green to brown, or green dotted reddish-brown. Bract blades are often shorter than the cluster, erect to ascending. Bracts at the base of auxiliary branches are more scale-like and green to brown.
Leaves and stems:
5 to 10 leaves, usually around 8, are alternately arranged along the stem, each 6 to 16 inches long and 4 to 8(12) mm wide. Lower leaf sheaths are pale. Stems are mostly erect, round in cross-section and smooth. Leaves and stems are typically bright yellowish-green. Plants form clumps from short rhizomes and a mix of flowering and vegetative shoots.
Fruit develops in late spring to midsummer, the mature achenes (seeds) dropping off individually and the scales dropping soon after. Scales are 1.7 to 2.2 mm long, lance-elliptic, brown to reddish-brown with a prominent midrib that extends to a short awn. Achenes are 1 to 1.2 mm long, to .8 mm wide, elliptic in outline, 3-sided, brown to reddish-brown at maturity. Surrounding the base are 6 light brown bristles that are several times longer than the achene and much contorted. The bristles mostly stay tightly scrunched and barely extend beyond the scale, if at all.
Scirpus pendulus is an uncommon wetland species found in wet ditches, meadows, and along swamp margins. Minnesota is on the fringe of its range, which extends from Nebraska to New England with scattered populations farther west, and there are only a few known occurrences here, mostly in grassy ditches. It closely resembles 3 other Minnesota Scirpus species: Scirpus atrocinctus, Scirpus pedicellatus, and Scirpus cyperinus. All share the common traits of a leafy round stem, leaf-like bracts, a terminal cluster with nodding branches and numerous small spikelets, and achenes with contorted bristles much longer than the achene. Scirpus pendulus, the least common of the 4, is most easily distinguished by the floral scales with prominent midribs, plus the bright yellow-green foliage. The other 3 species have floral scales with inconspicuous midribs and no hint of an awn, and are a medium to darker green.
Compare these with other Bulrush species, which may differ by their 3-sided stems, erect bracts that appear to be a continuation of the stem, essentially leafless stems, globular clusters of numerous small spikelets, bristles as long as or shorter than the achene, or other traits not as above.
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- Scirpus pendulus plants
- Scirpus pendulus grassy ditch habitat
- clumps are a mix of flowering and vegetative shoots
- spikelets are single and mostly stalked
- scales drop off starting from the bottom of the spikelet
Photos by K. Chayka and Peter M. Dziuk taken in Douglas County.
Have you seen this plant in Minnesota, or have any other comments about it?