Scirpus pedicellatus (Stalked Bulrush)
|Also known as:||Stalked Woolsedge|
|Habitat:||part shade, sun; wet; sandy shores, stream banks, marshes, meadows, bog edges|
|Fruiting season:||July - September|
|Plant height:||3 to 5 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 with numerous spikelets (flower clusters) all single, mostly on slender stalks, some stalkless. Spikelets are 3 to 9 mm long (to ~1/3 inch), narrowly egg-shaped to oval-elliptic, blunt at the tip, usually whitish to light 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 4 to 7 main branches, are leaf-like bracts with sheaths that are usually green to brown, occasionally blackish-brown. Bract blades are shorter than to much longer than the cluster, the shorter bracts erect to ascending and the longer bracts arching to reflexed (bent downward). Bracts at the base of auxiliary branches are more scale-like and brown.
Leaves and stems:
About 8 leaves are alternately arranged along the stem, each 16 to 30 inches long and 5 to 9 mm wide. Lower leaf sheaths are brown. Stems are mostly erect, round in cross-section and smooth. Plants form dense clumps from short rhizomes and a mix of flowering and vegetative shoots. Old leaves persist forming tussocks.
Fruit develops in mid to late summer, the mature achenes (seeds) dropping off individually and the scales dropping soon after. Scales are 1.4 to 1.8 mm long, oblong-elliptic, blunt at the tip sometimes with a minute point, whitish to light brown with a green or pale midrib that becomes rather inconspicuous; sometimes scales are blackish near the tip. Achenes are .7 to .9 mm long, to .5 mm wide, elliptic to urn-shaped in outline, 3-sided, straw-colored to whitish at maturity. Surrounding the base are 6 white to light brown bristles that are several times longer than the achene and much contorted. The bristles extend out beyond the scale and give the cluster a woolly appearance.
Scirpus pedicellatus is a wetland species found along lake and pond margins and in wet meadows and marshes, and reaches the western edge of its range in Minnesota. It closely resembles 3 other Minnesota Scirpus species: Scirpus atrocinctus, Scirpus cyperinus, and Scirpus pendulus. 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 pedicellatus is distinguished by about 8 leaves per stem, leaves up to 10 mm (~3/8 inch) wide, usually green to brown sheaths at the base of the cluster, light brown to whitish floral scales with an inconspicuous midrib, spikelets all single and mostly stalked, and the long, contorted, white to light brown bristles extending beyond the scale giving the cluster a woolly appearance at maturity. The sheath color is sometimes blackish-brown and scales sometimes blackish near the tip.
By comparison, S. cyperinus has spikelets that are clustered in groups of 3 to 7 or more, and mature heads are more dull rusty brown. S. pendulus has scales with a prominent midrib extending to a short awn, and brown bristles on the achene that are more tightly scrunched and do not extend beyond the scale at maturity. S. atrocinctus is most similar and can be very difficult to distinguish, but is generally less robust, has 4 to 7 leaves per stem, leaves only up to 6 mm (~¼ inch) wide, and blackish sheaths and scales. S. pedicellatus hybridizes with both S. cyperinus and S. atrocinctus and fertile intermediates may be found when both parents are present, the hybrids cross-breeding with themselves and their parents, known as a hybrid swarm. As if they weren't challenging enough already...
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 about as long as or shorter than the achene, or other traits not as above.
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- Scirpus pedicellatus plant
- Scirpus pedicellatus plant
- Scirpus pedicellatus plants
- a stand of Scirpus pedicellatus
- young Scirpus pedicellatus plants
- spikelets are single, mostly stalked
- spikelets are usually pale
- whole heads can look quite pale
Photos by K. Chayka taken in Aitkin, Lake and Ramsey counties. Photos courtesy Peter M. Dziuk taken in Stearns County.
Have you seen this plant in Minnesota, or have any other comments about it?