Scirpus georgianus (Georgia Bulrush)
|Also known as:|
|Habitat:||part shade, sun; moist to wet; meadows, shores, wet ditches, river banks, woodland edges, shallow marshes|
|Fruiting season:||May - July|
|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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Stiff, open or compact branching cluster at the top of the stem, the main branches up to 4 inches long and more or less radiating in all directions from a central point, usually with short, divergent branchlets at each branch tip. At the tip of each branchlet is a hemispheric to round head of 4 to 35 stalkless spikelets (flower clusters). Spikelets are 2 to 4 mm long (average ~1/8 inch), oval to egg-shaped, blunt at the tip, with the florets spirally arranged. Florets are perfect (both male and female parts) each with a 3-parted style and subtended by a single scale.
Often, bulblets form on one or more branches and sprout late in the season. At the base of the cluster are 3 leaf-like bracts, green at the base though may be brown or spotted reddish-brown along the edge. Bract blades are of varying lengths, shorter to longer than the cluster branches. Bracts at the base of auxiliary branches are shorter or more scale-like.
Leaves and stems:
6 to 12 leaves are alternately arranged along the stem, 7 to 20 inches long and 6 to 13 mm (to ~½ inch) wide. Lower leaf sheaths are green to light brown with a few to many cross-partitions (septa) that are usually not very conspicuous. Stems are erect, smooth and 3-sided in cross-section with rounded angles, and usually a few from the base forming loose clumps.
Fruit develops in early to mid-summer, the mature achenes (seeds) dropping off individually and the scales soon after, leaving behind naked branchlets. Scales are 1 to 1.8 mm long, oval-elliptic, the scale body rounded at the tip with a short pointed extension of the midrib. Scale color is brown or blackish-brown, the midrib paler. Achenes are .6 to 1.2 mm long, .4 to .5 mm wide, plumply to weakly 3-sided in cross-section, elliptic to urn-shaped in outline, pale brown to nearly white at maturity. Surrounding the base are 1 to 3 pale bristles that are usually rudimentary, rarely half as long as the achene, or may be absent altogether; bristles are smooth or with a few minute teeth near the tip.
Scirpus georgianus has only been recorded a handful of times in Minnesota, where it reaches the northwest fringe of its range. It is typically found in the wet to moist, often sandy soils of shores, meadows, wet ditches and marsh edges. It closely resembles 4 other Minnesota Scirpus species: Scirpus atrovirens, Scirpus hattorianus, Scirpus microcarpus, and Scirpus pallidus. These share the common traits of a weakly 3-sided stem, 3 or more stem leaves, 3 or more leaf-like bracts that are shorter to longer than the cluster branches, and a terminal cluster with fairly stiff erect to spreading branches that end in dense, hemispheric to round heads of several to many spikelets.
Scirpus georgianus is the least common of the 4 and is distinguished by 1 to 3 rudimentary bristles around the base of the achene, which are rarely more than half as long as the achene and may be absent altogether. In most other respects it resembles S. atrovirens and was at one time considered a var of that species. Both may have numerous cross-partitions (septa) on sheaths (most evident on lower sheaths, even when sheaths/leaves dry up), floral scales usually dark brown to brown-black at maturity with an awn not more than than .4mm long, 3-parted styles, and bulblets that sprout late in the season (usually present on at least some plants within a population). S. atrovirens septa tend to be conspicuous where S. georgianus are usually less so and may be few in number.
Due to these similarities, it is within the realm of possibility that S. georgianus is more widespread in the state than records indicate, just overlooked and assumed to be the common S. atrovirens. With so few records of it in Minnesota, we never expected to find it here ourselves, but luck came our way after Jason Husveth alerted us to a small population he stumbled upon at the edge of an old farm field in Lino Lakes. He has a good eye! S. georgianus is not currently considered a rare species in Minnesota but is tracked by the DNR; it is currently listed as a Special Concern species in Wisconsin.
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- Scirpus georgianus plants
- Scirpus georgianus plants
- comparison of Scirpus georgianus and S. atrovirens achenes
Photos by K. Chayka taken in Anoka County.
Have you seen this plant in Minnesota, or have any other comments about it?